Shielded electrical cable in twinaxial configuration

ABSTRACT

A shielded electrical cable includes one or more conductor sets extending along a length of the cable and being spaced apart from each other along a width of the cable. Each conductor set has one or more conductors having a size no greater than 24 AWG and each conductor set has an insertion loss of less than about −20 dB/meter over a frequency range of 0 to 20 GHz. First and second shielding films are disposed on opposite sides of the cable, the first and second films including cover portions and pinched portions arranged such that, in transverse cross section, the cover portions of the first and second films in combination substantially surround each conductor set, and the pinched portions of the first and second films in combination form pinched portions of the cable on each side of each conductor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2010/060640, filed Dec. 16, 2010, which claims priority to U.S.Provisional Application No. 61/378,902, filed Aug. 31, 2010, thedisclosures of which are incorporated by reference in their entiretyherein.

TECHNICAL FIELD

The present disclosure relates generally to electrical cables andconnectors.

BACKGROUND

Electrical cables for transmission of electrical signals are well known.One common type of electrical cable is a coaxial cable. Coaxial cablesgenerally include an electrically conductive wire surrounded by aninsulator. The wire and insulator are surrounded by a shield, and thewire, insulator, and shield are surrounded by a jacket. Another commontype of electrical cable is a shielded electrical cable comprising oneor more insulated signal conductors surrounded by a shielding layerformed, for example, by a metal foil. To facilitate electricalconnection of the shielding layer, a further un-insulated conductor issometimes provided between the shielding layer and the insulation of thesignal conductor or conductors. Both these common types of electricalcable normally require the use of specifically designed connectors fortermination and are often not suitable for the use of mass-terminationtechniques, i.e., the simultaneous connection of a plurality ofconductors to individual contact elements, such as contacts of anelectrical connector or contact elements on a printed circuit board.

SUMMARY

A shielded electrical cable includes one or more conductor setsextending along a length of the cable and being spaced apart from eachother along a width of the cable. Each conductor set has one or moreconductors having a size no greater than 24 AWG and each conductor sethas an insertion loss of less than −20 dB/meter over a frequency rangeof 0 to 20 GHz. First and second shielding films are disposed onopposite sides of the cable, the first and second films including coverportions and pinched portions arranged such that, in transverse crosssection, the cover portions of the first and second films in combinationsubstantially surround each conductor set, and the pinched portions ofthe first and second films in combination form pinched portions of thecable on each side of each conductor. A maximum separation between thefirst cover portions of the first and second shielding films is D, aminimum separation between the first pinched portions of the first andsecond shielding films is d₁, and d₁/D is less than about 0.25.

The conductor set may comprise two conductors in a twinaxial arrangementand the insertion loss due to resonance of the conductor set may beabout zero.

The conductor set may comprise two conductors in a twinaxialarrangement, and a nominal insertion loss without insertion loss due toresonance may be about 0.5 times the insertion loss due to resonance ofthe conductor set.

The cable may include an adhesive layer disposed between the pinchedportions of the shielding films.

The insertion loss of each conductor set may be less than about −5 dBper meter or about −4 dB per meter, or about −3 dB per meter.

The cable may have a skew of less than about 20 psec/meter or less thanabout 10 psec/meter at data transfer speeds of up to about 10 Gbps.

The cable may have a characteristic impedance that remains within 5-10%of a target characteristic impedance over a cable length of about 1meter.

One or more conductor sets of the cable may comprise a first conductorset and a second conductor set, each conductor set having a firstinsulated conductor and a second insulated conductor and a highfrequency electrical isolation of the first insulated conductor relativeto the second insulated conductor in each conductor set may besubstantially less than a high frequency electrical isolation of thefirst conductor set relative to an adjacent conductor set.

The high frequency isolation of the first insulated conductor relativeto the second conductor is a first far end crosstalk C1 at a specifiedfrequency range of 5-15 GHz and a length of 1 meter, and the highfrequency isolation of the first conductor set relative to the adjacentconductor set is a second far end crosstalk C2 at the specifiedfrequency. C2 can be at least 10 dB lower than C1.

The cable may have d₁/D less than 0.1.

A shielded electrical cable includes a plurality of conductor setsextending along a length of the cable and being spaced apart from eachother along a width of the cable, each conductor set having twoconductors having a size no greater than 24 AWG and each conductor sethaving a signal attenuation of less than −20 dB/meter over a frequencyrange of 0 to 20 GHz. The cable also includes a drain wire and first andsecond shielding films disposed on opposite sides of the cable, thefirst and second shielding films including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films, in combination, substantiallysurround each conductor set, and the pinched portions of the first andsecond films, in combination, form pinched portions of the cable on eachside of each conductor set. For at least one conductor set, a separationbetween the drain wire and a closest conductor of the conductor set maybe greater than 0.5 times a center to center spacing between the twoconductors of the conductor set.

A shielded electrical cable may include a plurality of conductor setsextending along a length of the cable and being spaced apart from eachother along a width of the cable, each conductor sets having twoconductors arranged in a twinaxial configuration, each of the conductorshaving a size no greater than 24 AWG. First and second shielding filmsare disposed on opposite sides of the cable, neither shielding filmcomprises a longitudinal fold that orients the shielding film to coverthe conductor sets on both sides of the cable. Each conductor set has aninsertion loss of less than −20 dB/meter over a frequency range of 0 to20 GHz and an insertion loss due to resonance of the conductor set isabout zero.

The cable may also include at least one drain wire, wherein the firstand second shielding films include cover portions and pinched portionsarranged such that, in transverse cross section, the cover portions ofthe first and second films, in combination, substantially surround eachconductor set, and the pinched portions of the first and second films,in combination, form pinched portions of the cable on each side of eachconductor set, wherein, for at least one conductor set, a separationbetween the center of the drain wire and the center of closest conductorof the conductor set can be greater than 0.5 times a center to centerspacing between the two conductors of the conductor set.

A shielded electrical cable includes a plurality of conductor setsextending along a length of the cable and being spaced apart from eachother along a width of the cable, each of the conductors sets comprisingtwo conductors arranged in a twinaxial configuration, neither conductorhaving a size greater than 24 AWG. First and second shielding films aredisposed on opposite sides of the cable, neither shielding filmcomprising a seam that bonds the shielding film to itself, wherein eachconductor set has an insertion loss of less than −20 dB/meter over afrequency range of 0 to 20 GHz and an insertion loss due to resonanceloss of the conductor set is about zero.

Each shielding film, individually, may surround less than all of aperiphery of each conductor set.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The Figures and detailed description that follow below moreparticularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of a shieldedelectrical cable;

FIGS. 2 a-2 g are front cross-sectional views of seven exemplaryembodiments of a shielded electrical cable;

FIG. 3 is a perspective view of two shielded electrical cables of FIG. 1terminated to a printed circuit board.

FIGS. 4 a-4 d are top views of an exemplary termination process of ashielded electrical cable;

FIG. 5 is a top view of another exemplary embodiment of a shieldedelectrical cable;

FIG. 6 is a top view of another exemplary embodiment of a shieldedelectrical cable;

FIGS. 7 a-7 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIGS. 8 a-8 c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable;

FIGS. 9 a-9 b are top and partially cross-sectional front views,respectively, of an exemplary embodiment of an electrical assemblyterminated to a printed circuit board.

FIGS. 10 a-10 e and 10 f-10 g are perspective and front cross-sectionalviews, respectively, illustrating an exemplary method of making ashielded electrical cable;

FIGS. 11 a-11 c are front cross-sectional views illustrating a detail ofan exemplary method of making a shielded electrical cable;

FIGS. 12 a-12 b are a front cross-sectional view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention and a corresponding detail view, respectively.

FIGS. 13 a-13 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention.

FIGS. 14 a-14 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable;

FIGS. 15 a-15 c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable;

FIGS. 16 a-16 g are front cross-sectional detail views illustratingseven exemplary embodiments of a parallel portion of a shieldedelectrical cable;

FIGS. 17 a-17 b are front cross-sectional detail views of anotherexemplary embodiment of a parallel portion of a shielded electricalcable;

FIG. 18 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable in a bent configuration.

FIG. 19 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable;

FIGS. 20 a-20 f are front cross-sectional detail views illustrating sixother exemplary embodiments of a parallel portion of a shieldedelectrical cable;

FIGS. 21-22 are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable;

FIG. 23 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 24 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 25 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 26 a-26 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 27 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 28 a-28 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 29 a-29 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 30 a is a perspective view of a shielded electrical cable assemblythat may utilize high packing density of the conductor sets;

FIGS. 30 b and 30 c are front cross-sectional views of exemplaryshielded electrical cables, which figures also depict parameters usefulin characterizing the density of the conductor sets;

FIG. 30 d is a top view of an exemplary shielded electrical cableassembly in which a shielded cable is attached to a terminationcomponent, and FIG. 30 e is a side view thereof;

FIGS. 30 f and 30 g are photographs of a shielded electrical cable thatwas fabricated;

FIG. 31 a is a front cross-sectional view of an exemplary shieldedelectrical cable showing some possible drain wire positions;

FIGS. 31 b and 31 c are detailed front cross-sectional views of aportion of a shielded cable, demonstrating one technique for providingon-demand electrical contact between a drain wire and shielding film(s)at a localized area;

FIG. 31 d is a schematic front cross-sectional view of a cable showingone procedure for treating the cable at a selected area to provideon-demand contact;

FIGS. 31 e and 31 f are top views of a shielded electrical cableassembly, showing alternative configurations in which one may choose toprovide on-demand contact between drain wires and shielding film(s);

FIG. 31 g is a top view of another shielded electrical cable assembly,showing another configuration in which one may choose to provideon-demand contact between drain wires and shielding film(s);

FIG. 32 a is a photograph of a shielded electrical cable that wasfabricated and treated to have on-demand drain wire contacts, and FIG.32 b is an enlarged detail of a portion of FIG. 32 a, and FIG. 32 c is aschematic representation of a front elevational view of one end of thecable of FIG. 32 a;

FIG. 32 d is a top view of a shielded electrical cable assembly thatemploys multiple drain wires coupled to each other through a shieldingfilm;

FIG. 32 e is a top view of another shielded electrical cable assemblythat employs multiple drain wires coupled to each other through ashielding film, the assembly being arranged in a fan-out configuration,and FIG. 32 f is a cross-sectional view of the cable at line 32 g-32 gof FIG. 32 e;

FIG. 33 a is a top view of another shielded electrical cable assemblythat employs multiple drain wires coupled to each other through ashielding film, the assembly also being arranged in a fan-outconfiguration, and FIG. 33 b is a cross-sectional view of the cable atline 33 b-33 b of FIG. 33 a;

FIGS. 33 c-f are schematic front cross-sectional views of shieldedelectrical cables having mixed conductor sets;

FIG. 33 g is a schematic front cross-sectional view of another shieldedelectrical cable having mixed conductor sets, and FIG. 33 hschematically depicts groups of low speed insulated conductor setsuseable in a mixed conductor set shielded cable;

FIGS. 34 a, 34 b, and 34 c are schematic top views of shielded cableassemblies in which a termination component of the assembly includes oneor more conduction path that re-routes one or more low speed signallines from one end of the termination component to the other; and

FIG. 34 d is a photograph of a mixed conductor set shielded cableassembly that was fabricated.

FIG. 35 a is a perspective view of an example cable construction;

FIG. 35 b is a cross section view of the example cable construction ofFIG. 35 a;

FIGS. 35 c-35 e are a cross section views of example alternate cableconstructions;

FIG. 35 f is a cross section of a portion of an example cable showingdimensions of interest;

FIGS. 35 g and 35 h are block diagrams illustrating steps of an examplemanufacturing procedure;

FIG. 36 a is a graph illustrating results of analysis of example cableconstructions;

FIG. 36 b is a cross section showing additional dimensions of interestrelative to the analysis of FIG. 36 a;

FIG. 36 c is a front cross-sectional view of a portion of anotherexemplary shielded electrical cable;

FIG. 36 d is a front cross-sectional view of a portion of anotherexemplary shielded electrical cable;

FIG. 36 e is a front cross-sectional views of other portions ofexemplary shielded electrical cables;

FIG. 36 f is a front cross-sectional view of another exemplary shieldedelectrical cable;

FIGS. 36 g-37 c are front cross-sectional views of further exemplaryshielded electrical cables;

FIGS. 38 a-38 d are top views that illustrate different procedures of anexemplary termination process of a shielded electrical cable to atermination component;

FIGS. 39 a-39 c are front cross-sectional views of still furtherexemplary shielded electrical cables; and

FIG. 40 is a graph of the insertion loss of a shielded electrical cablehaving 30 AWG silver plated conductors;

FIG. 41 is a graph of the insertion loss of a shielded electrical cablehaving 30 AWG tin plated conductors;

FIG. 42 shows a cable that has a wrapped shield;

FIG. 43 is a photograph of the cross section of twinaxial configurationof a shielded electrical cable;

FIG. 44 are graphs that compare the insertion loss due to resonance of acable having a wrapped shield with a cable having two shielding filmswith cover portions and pinched portions as described herein;

FIG. 45 shows insertion low for three different cable lengths;

FIG. 46 shows a cable that has a longitudinally folded shield;

FIG. 47 is a graph comparing the electrical isolation performance of twosample cables;

FIG. 48 is a block diagram illustrating an example test setup formeasuring force versus deflection of a cable;

FIGS. 49 and 50 are graphs showing results of example force-deflectiontests for cables; and

FIG. 51 is a logarithmic graph summarizing average values offorce-deflection tests for example cables.

DETAILED DESCRIPTION

As the number and speed of interconnected devices increases, electricalcables that carry signals between such devices need to be smaller andcapable of carrying higher speed signals without unacceptableinterference or crosstalk. Shielding is used in some electrical cablesto reduce interactions between signals carried by neighboringconductors. Many of the cables described herein have a generally flatconfiguration, and include conductor sets that extend along a length ofthe cable, as well as electrical shielding films disposed on oppositesides of the cable. Pinched portions of the shielding films betweenadjacent conductor sets help to electrically isolate the conductor setsfrom each other. Many of the cables also include drain wires thatelectrically connect to the shields, and extend along the length of thecable. The cable configurations described herein can help to simplifyconnections to the conductor sets and drain wires, reduce the size ofthe cable connection sites, and/or provide opportunities for masstermination of the cable.

FIG. 1 illustrates an exemplary shielded electrical cable 2 thatincludes a plurality of conductor sets 4 spaced apart from each otheralong all or a portion of a width, w, of the cable 2 and extend along alength, L, of the cable 2. The cable 2 may be arranged generally in aplanar configuration as illustrated in FIG. 1 or may be folded at one ormore places along its length into a folded configuration. In someimplementations, some parts of cable 2 may be arranged in a planarconfiguration and other parts of the cable may be folded. In someconfigurations, at least one of the conductor sets 4 of the cable 2includes two insulated conductors 6 extending along a length, L, ofcable 2. The two insulated conductors 6 of the conductor sets 4 may bearranged substantially parallel along all or a portion of the length, L,of the cable 2. Insulated conductors 6 may include insulated signalwires, insulated power wires, or insulated ground wires. Two shieldingfilms 8 are disposed on opposite sides of the cable 2.

The first and second shielding films 8 are arranged so that, intransverse cross section, cable 2 includes cover regions 14 and pinchedregions 18. In the cover regions 14 of the cable 2, cover portions 7 ofthe first and second shielding films 8 in transverse cross sectionsubstantially surround each conductor set 4. For example, cover portionsof the shielding films may collectively encompass at least 70%, or atleast 75%, or at least 80%, or at least 85% or at least 90% of theperimeter of any given conductor set. Pinched portions 9 of the firstand second shielding films form the pinched regions 18 of cable 2 oneach side of each conductor set 4. In the pinched regions 18 of thecable 2, one or both of the shielding films 8 are deflected, bringingthe pinched portions 9 of the shielding films 8 into closer proximity.In some configurations, as illustrated in FIG. 1, both of the shieldingfilms 8 are deflected in the pinched regions 18 to bring the pinchedportions 9 into closer proximity. In some configurations, one of theshielding films may remain relatively flat in the pinched regions 18when the cable is in a planar or unfolded configuration, and the othershielding film on the opposite side of the cable may be deflected tobring the pinched portions of the shielding film into closer proximity.

The conductors 6 may comprise any suitable conductive material and mayhave a variety of cross sectional shapes and sizes. For example, incross section, the conductors and/or ground wires may be circular, oval,rectangular or any other shape. One or more conductors and/or groundwires in a cable may have one shape and/or size that differs from otherone or more conductors and/or ground wires in the cable. The conductorsand/or ground wires may be solid or stranded wires. All of theconductors and/or ground wires in a cable may be stranded, all may besolid, or some may be stranded and some solid. Stranded conductorsand/or ground wires may take on different sizes and/or shapes. Theconnectors and/or ground wires may be coated or plated with variousmetals and/or metallic materials, including gold, silver, tin, and/orother materials.

The material used to insulate the conductors of the conductor sets maybe any suitable material that achieves the desired electrical propertiesof the cable. In some cases, the insulation used may be a foamedinsulation which includes air to reduce the dielectric constant and theoverall thickness of the cable.

The shielding films 8 may comprise a conductive material including butnot limited to copper, silver, aluminum, gold, and/or alloys thereof.The shielding films 8 may comprise multiple layers of conductive and/ornon-conductive layers. In some cases one or more of the shielding films8 may include a conductive layer comprising the conductive material anda non-conductive polymeric layer. The shielding films 8 may have athickness in the range of 0.01 mm to 0.05 mm and the overall thicknessof the cable may be less than 2 mm or less than 1 mm.

The cable 2 may also include an adhesive layer 10 disposed betweenshielding films 8 at least between the pinched portions 9. The adhesivelayer 10 bonds the pinched portions 9 of the shielding films 8 to eachother in the pinched regions 18 of the cable 2. The adhesive layer 10may or may not be present in the cover region 14 of the cable 2.

In some cases, conductor sets 4 have a substantiallycurvilinearly-shaped envelope or perimeter in transverse cross-section,and shielding films 8 are disposed around conductor sets 4 such as tosubstantially conform to and maintain the cross-sectional shape along atleast part of, and preferably along substantially all of, the length Lof the cable 6. Maintaining the cross-sectional shape maintains theelectrical characteristics of conductor sets 4 as intended in the designof conductor sets 4. This is an advantage over some conventionalshielded electrical cables where disposing a conductive shield around aconductor set changes the cross-sectional shape of the conductor set.

Although in the embodiment illustrated in FIG. 1, each conductor set 4has two insulated conductors 6; in other embodiments, some or all of theconductor sets may include only one insulated conductor, or may includemore than two insulated conductors 6. For example, an alternativeshielded electrical cable similar in design to that of FIG. 1 mayinclude one conductor set that has eight insulated conductors 6, oreight conductor sets each having only one insulated conductor 6. Thisflexibility in arrangements of conductor sets and insulated conductorsallows the disclosed shielded electrical cables to be configured in waysthat are suitable for a wide variety of intended applications. Forexample, the conductor sets and insulated conductors may be configuredto form: a multiple twinaxial cable, i.e., multiple conductor sets eachhaving two insulated conductors; a multiple coaxial cable, i.e.,multiple conductor sets each having only one insulated conductor; orcombinations thereof. In some embodiments, a conductor set may furtherinclude a conductive shield (not shown) disposed around the one or moreinsulated conductors, and an insulative jacket (not shown) disposedaround the conductive shield.

In the embodiment illustrated in FIG. 1, shielded electrical cable 2further includes optional ground conductors 12. Ground conductors 12 mayinclude ground wires or drain wires. Ground conductors 12 can be spacedapart from and extend in substantially the same direction as insulatedconductors 6. Shielding films 8 can be disposed around ground conductors12. The adhesive layer 10 may bond shielding films 8 to each other inthe pinched portions 9 on both sides of ground conductors 12. Groundconductors 12 may electrically contact at least one of the shieldingfilms 8.

The cross-sectional views of FIGS. 2 a-2 g may represent variousshielded electrical cables, or portions of cables. In FIG. 2 a, shieldedelectrical cable 102 a includes a single conductor set 104. Conductorset 104 extends along the length of the cable and has only a singleinsulated conductor 106. If desired, the cable 102 a may be made toinclude multiple conductor sets 104 spaced apart from each other acrossa width of the cable 102 a and extending along a length of the cable.Two, shielding films 108 are disposed on opposite sides of the cable.The cable 102 a includes a cover region 114 and pinched regions 118. Inthe cover region 114 of the cable 102 a, the shielding films 108 includecover portions 107 that cover the conductor set 104. In transverse crosssection, the cover portions 107, in combination, substantially surroundthe conductor set 104. In the pinched regions 118 of the cable 102 a,the shielding films 108 include pinched portions 109 on each side of theconductor set 104.

An optional adhesive layer 110 may be disposed between shielding films108. Shielded electrical cable 102 a further includes optional groundconductors 112. Ground conductors 112 are spaced apart from and extendin substantially the same direction as insulated conductor 106.Conductor set 104 and ground conductors 112 can be arranged so that theylie generally in a plane as illustrated in FIG. 2 a.

Second cover portions 113 of shielding films 108 are disposed around,and cover, the ground conductors 112. The adhesive layer 110 may bondthe shielding films 108 to each other on both sides of ground conductors112. Ground conductors 112 may electrically contact at least one ofshielding films 108. In FIG. 2 a, insulated conductor 106 and shieldingfilms 108 are effectively arranged in a coaxial cable configuration. Thecoaxial cable configuration of FIG. 2 a can be used in a single endedcircuit arrangement.

As illustrated in the transverse cross sectional view of FIG. 2 a, thereis a maximum separation, D, between the cover portions 107 of theshielding films 108, and there is a minimum separation, d₁, between thepinched portions 109 of the shielding films 108.

FIG. 2 a shows the adhesive layer 110 disposed between the pinchedportions 109 of the shielding films 108 in the pinched regions 118 ofthe cable 102 a and disposed between the cover portions 107 of theshielding films 108 and the insulated conductor 106 in the cover region114 of the cable 102 a. In this arrangement, the adhesive layer 110bonds the pinched portions 109 of the shielding films 108 together inthe pinched regions 118 of the cable, and bonds the cover portions 107of the shielding films 108 to the insulated conductor 106 in the coverregion 114 of the cable 102 a.

Shielded cable 102 b of FIG. 2 b is similar to cable 102 a of FIG. 2 a,with similar elements identified by similar reference numerals, exceptthat in FIG. 2 b, the optional adhesive layer 110 b is not presentbetween the cover portions 107 of the shielding films 108 and theinsulated conductor 106 in the cover region 114 of the cable 102 b. Inthis arrangement, the adhesive layer 110 b bonds the pinched portions109 of the shielding films 108 together in the pinched regions 118 ofthe cable, but the adhesive layer 110 b does not bond cover portions 107of the shielding films 108 to the insulated conductor 106 in the coverregions 114 of the cable 102 b.

Referring to FIG. 2 c, shielded electrical cable 202 c is similar toshielded electrical cable 102 a of FIG. 2 a, except that cable 202 c hasa single conductor set 204 which has two insulated conductors 206. Ifdesired, the cable 202 c may be made to include multiple conductor sets204 spaced part across a width of the cable 202 c and extending along alength of the cable. Insulated conductors 206 are arranged generally ina single plane and effectively in a twinaxial configuration. The twinaxial cable configuration of FIG. 2 c can be used in a differential paircircuit arrangement or in a single ended circuit arrangement.

Two shielding films 208 are disposed on opposite sides of conductor set204. The cable 202 c includes a cover region 214 and pinched regions218. In the cover region 214 of the cable 202, the shielding films 208include cover portions 207 that cover the conductor set 204. Intransverse cross section, the cover portions 207, in combination,substantially surround the conductor set 204. In the pinched regions 218of the cable 202, the shielding films 208 include pinched portions 209on each side of the conductor set 204.

An optional adhesive layer 210 c may be disposed between shielding films208. Shielded electrical cable 202 c further includes optional groundconductors 212 c similar to ground conductors 112 discussed previously.Ground conductors 212 c are spaced apart from, and extend insubstantially the same direction as, insulated conductors 206 c.Conductor set 204 c and ground conductors 212 c can be arranged so thatthey lie generally in a plane as illustrated in FIG. 2 c.

As illustrated in the cross section of FIG. 2 c, there is a maximumseparation, D, between the cover portions 207 c of the shielding films208 c; there is a minimum separation, d₁, between the pinched portions209 c of the shielding films 208 c; and there is a minimum separation,d₂, between the shielding films 208 c between the insulated conductors206 c.

FIG. 2 c shows the adhesive layer 210 c disposed between the pinchedportions 209 of the shielding films 208 in the pinched regions 218 ofthe cable 202 and disposed between the cover portions 207 of theshielding films 208 and the insulated conductors 206 in the cover region214 of the cable 202 c. In this arrangement, the adhesive layer 210 cbonds the pinched portions 209 of the shielding films 208 together inthe pinched regions 218 of the cable 202 c, and also bonds the coverportions 207 of the shielding films 208 to the insulated conductors 206in the cover region 214 of the cable 202 c.

Shielded cable 202 d of FIG. 2 d is similar to cable 202 c of FIG. 2 c,with similar elements identified by similar reference numerals, exceptthat in cable 202 d the optional adhesive layer 210 d is not presentbetween the cover portions 207 of the shielding films 208 and theinsulated conductors 206 in the cover region 214 of the cable. In thisarrangement, the adhesive layer 210 d bonds the pinched portions 209 ofthe shielding films 208 together in the pinched regions 218 of thecable, but does not bond the cover portions 207 of the shielding films208 to the insulated conductors 206 in the cover region 214 of the cable202 d.

Referring now to FIG. 2 e, we see there a transverse cross-sectionalview of a shielded electrical cable 302 similar in many respects to theshielded electrical cable 102 a of FIG. 2 a. However, where cable 102 aincludes a single conductor set 104 having only a single insulatedconductor 106, cable 302 includes a single conductor set 304 that hastwo insulated conductors 306 extending along a length of the cable 302.Cable 302 may be made to have multiple conductor sets 304 spaced apartfrom each other across a width of the cable 302 and extending along alength of the cable 302. Insulated conductors 306 are arrangedeffectively in a twisted pair cable arrangement, whereby insulatedconductors 306 twist around each other and extend along a length of thecable 302.

FIG. 2 f depicts another shielded electrical cable 402 that is alsosimilar in many respects to the shielded electrical cable 102 a of FIG.2 a. However, where cable 102 a includes a single conductor set 104having only a single insulated conductor 106, cable 402 includes asingle conductor set 404 that has four insulated conductors 406extending along a length of the cable 402. The cable 402 may be made tohave multiple conductor, sets 404 spaced apart from each other across awidth of the cable 302 and extending along a length of the cable 302.

Insulated conductors 306 are arranged effectively in a quad cablearrangement, whereby insulated conductors 306 may or may not around eachother as insulated conductors 106 f extend along a length of the cable302.

Referring back to FIGS. 2 a-2 f, further embodiments of shieldedelectrical cables may include a plurality of spaced apart conductor sets104, 204, 304, or 404, or combinations thereof, arranged generally in asingle plane. Optionally, the shielded electrical cables may include aplurality of ground conductors 112 spaced apart from, and extendinggenerally in the same direction as, the insulated conductors of theconductor sets. In some configurations, the conductor sets and groundconductors can be arranged generally in a single plane. FIG. 2 gillustrates an exemplary embodiment of such a shielded electrical cable.

Referring to FIG. 2 g, shielded electrical cable 502 includes aplurality of spaced apart conductor sets 504 a, 504 b arranged generallyin plane. Shielded electrical cable 504 further includes optional groundconductors 112 disposed between conductor sets 504 a, 504 b and at bothsides or edges of shielded electrical cable 504.

First and second shielding films 508 are disposed on opposite sides ofthe cable 504 and are arranged so that, in transverse cross section, thecable 504 includes cover regions 524 and pinched regions 528. In thecover regions 524 of the cable, cover portions 517 of the first andsecond shielding films 508 in transverse cross section substantiallysurround each conductor set 504 a, 506 b. For example, the coverportions of the first and second shielding films in combinationsubstantially surround each conductor set by encompassing at least 70%,or at least 75%, or at least 80%, or at least 85% or at least 90% of aperiphery of each conductor set. Pinched portions 519 of the first andsecond shielding films 508 form the pinched regions 518 on two sides ofeach conductor set 504 a, 504 b.

The shielding films 508 are disposed around ground conductors 112. Anoptional adhesive layer 510 is disposed between shielding films 208 andbonds the pinched portions 519 of the shielding films 508 to each otherin the pinched regions 528 on both sides of each conductor set 504 a,504 b. Shielded electrical cable 502 includes a combination of coaxialcable arrangements (conductor sets 504 a) and a twinaxial cablearrangement (conductor set 504 b) and may therefore be referred to as ahybrid cable arrangement.

FIG. 3 illustrates two shielded electrical cables 2 terminated to aprinted circuit board 14. Because insulated conductors 6 and groundconductors 12 can be arranged generally in a single plane, shieldedelectrical cables 2 are well suited for mass-stripping, i.e., thesimultaneous stripping of shielding films 8 and insulated conductors 6,and mass-termination, i.e., the simultaneous terminating of the strippedends of insulated conductors 6 and ground conductors 12, which allows amore automated cable assembly process. In FIG. 3, the stripped ends ofinsulated conductors 6 and ground conductors 12 are terminated tocontact elements 16 on printed circuit board 14. The stripped ends ofinsulated conductors and ground conductors may be terminated to anysuitable individual contact elements of any suitable termination point,such as, e.g., electrical contacts of an electrical connector.

FIGS. 4 a-4 d illustrate an exemplary termination process of shieldedelectrical cable 302 to a printed circuit board or other terminationcomponent 314. This termination process can be a mass-terminationprocess and includes the steps of stripping (illustrated in FIGS. 4 a-4b), aligning (illustrated in FIG. 4 c), and terminating (illustrated inFIG. 4 d). When forming shielded electrical cable 302, which may ingeneral take the form of any of the cables shown and/or describedherein, the arrangement of conductor sets 304, insulated conductors 306,and ground conductors 312 of shielded electrical cable 302 may bematched to the arrangement of contact elements 316 on printed circuitboard 314, which would eliminate any significant manipulation of the endportions of shielded electrical cable 302 during alignment ortermination.

In the step illustrated in FIG. 4 a, an end portion 308 a of shieldingfilms 308 is removed. Any suitable method may be used, such as, e.g.,mechanical stripping or laser stripping. This step exposes an endportion of insulated conductors 306 and ground conductors 312. In oneaspect, mass-stripping of end portion 308 a of shielding films 308 ispossible because they form an integrally connected layer that isseparate from the insulation of insulated conductors 306. Removingshielding films 308 from insulated conductors 306 allows protectionagainst electrical shorting at these locations and also providesindependent movement of the exposed end portions of insulated conductors306 and ground conductors 312. In the step illustrated in FIG. 4 b, anend portion 306 a of the insulation of insulated conductors 306 isremoved. Any suitable method may be used, such as, e.g., mechanicalstripping or laser stripping. This step exposes an end portion of theconductor of insulated conductors 306. In the step illustrated in FIG. 4c, shielded electrical cable 302 is aligned with printed circuit board314 such that the end portions of the conductors of insulated conductors306 and the end portions of ground conductors 312 of shielded electricalcable 302 are aligned with contact elements 316 on printed circuit board314. In the step illustrated in FIG. 3 d, the end portions of theconductors of insulated conductors 306 and the end portions of groundconductors 312 of shielded electrical cable 302 are terminated tocontact elements 316 on printed circuit board 314. Examples of suitabletermination methods that may be used include soldering, welding,crimping, mechanical clamping, and adhesively bonding, to name a few.

FIG. 5 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 602 is similar in some respects to shielded electricalcable 2 illustrated in FIG. 1. In addition, shielded electrical cable602 includes a one or more longitudinal slits or splits 18 disposedbetween conductor sets 4. The splits 18 separate individual conductorsets at least along a portion of the length of shielded electrical cable602, thereby increasing at least the lateral flexibility of the cable602. This may allow, for example, the shielded electrical cable 602 tobe placed more easily into a curvilinear outer jacket. In otherembodiments, splits 18 may be placed such as to separate individual ormultiple conductor sets 4 and ground conductors 12. To maintain thespacing of conductor sets 4 and ground conductors 12, splits 18 may bediscontinuous along the length of shielded electrical cable 602. Tomaintain the spacing of conductor sets 4 and ground conductors 12 in atleast one end portion A of shielded electrical cable 602 so as tomaintain mass-termination capability, the splits 18 may not extend intoone or both end portions A of the cable. Splits 18 may be formed inshielded electrical cable 602 using any suitable method, such as, e.g.,laser cutting or punching. Instead of or in combination withlongitudinal splits, other suitable shapes of openings may be formed inthe disclosed electrical cable 602, such as, e.g., holes, e.g., toincrease at least the lateral flexibility of the cable 602.

FIG. 6 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 702 is similar to shielded electrical cable 602illustrated in FIG. 5. Effectively, in shielded electrical cable 702,one of conductor sets 4 is replaced by two ground conductors 12.Shielded electrical cable 702 includes longitudinal splits 18 and 18′.Split 18 separates individual conductor sets 4 along a portion of thelength of shielded electrical cable 702 and does not extend into endportions A of shielded′electrical cable 702. Split 18′ separatesindividual conductor sets 4 along the length of shielded electricalcable 702 and extends into end portions A of shielded electrical cable702, which effectively splits shielded electrical cable 702 into twoindividual shielded electrical cables 702′, 702″. Shielding films 8 andground conductors 12 provide an uninterrupted ground plane in each ofthe individual shielded electrical cables 702′, 702″. This exemplaryembodiment illustrates the advantage of the parallel processingcapability of the shielded electrical cables according to aspects of thepresent invention, whereby multiple shielded electrical cables may beformed simultaneously.

The shielding films used in the disclosed shielded cables can have avariety of configurations and can be made in a variety of ways. FIGS. 7a-7 d illustrate four exemplary embodiments of a shielded electricalcable according to aspects of the present invention. FIGS. 7 a-7 dillustrate various examples of constructions of the shielding films ofthe shielded electrical cables. In one aspect, at least one of theshielding films may include a conductive layer and a non-conductivepolymeric layer. The conductive layer may include any suitableconductive material, including but not limited to copper, silver,aluminum, gold, and alloys thereof. The non-conductive polymeric layermay include any suitable polymeric material, including but not limitedto polyester, polyimide, polyamide-imide, polytetrafluoroethylene,polypropylene, polyethylene, polyphenylene, sulfide, polyethylenenaphthalate, polycarbonate, silicone rubber, ethylene propylene dienerubber, polyurethane, acrylates, silicones, natural rubber, epoxies, andsynthetic rubber adhesive. The non-conductive polymeric layer mayinclude one or more additives and/or fillers to provide propertiessuitable for the intended application. In another aspect, at least oneof the shielding films may include a laminating adhesive layer disposedbetween the conductive layer and the non-conductive polymeric layer. Forshielding films that have a conductive layer disposed on anon-conductive layer, or that otherwise have one major exterior surfacethat is electrically conductive and an opposite major exterior surfacethat is substantially non-conductive, the shielding film may beincorporated into the shielded cable in several different orientationsas desired. In some cases, for example, the conductive surface may facethe conductor sets of insulated wires and ground wires, and in somecases the non-conductive surface may face those components. In caseswhere two shielding films are used on opposite sides of the cable, thefilms may be oriented such that their conductive surfaces face eachother and each face the conductor sets and ground wires, or they may beoriented such that their non-conductive surfaces face each other andeach face the conductor sets and ground wires, or they may be orientedsuch that the conductive surface of one shielding film faces theconductor sets and ground wires, while the non-conductive surface of theother shielding film faces conductor sets and ground wires from theother side of the cable.

In some cases, at least one of the shielding films may include astand-alone conductive film, such as a compliant or flexible metal foil.The construction of the shielding films may be selected based on anumber of design parameters suitable for the intended application, suchas, e.g., flexibility, electrical performance, and configuration of theshielded electrical cable (such as, e.g., presence and location ofground conductors). In some cases, the shielding films have anintegrally formed construction. In some cases, the shielding films mayhave a thickness in the range of 0.01 mm to 0.05 mm. The shielding filmsdesirably provide isolation, shielding, and precise spacing between theconductor sets, and allow for a more automated and lower cost cablemanufacturing process. In addition, the shielding films preventinsertion loss due to resonance of the cable, a phenomenon known as“signal suck-out”, whereby high signal attenuation occurs at aparticular frequency range. This phenomenon typically occurs inconventional shielded electrical cables where a conductive shield iswrapped around a conductor set.

FIG. 7 a is a cross sectional view across a width of a shieldedelectrical cable 802 that shows a single conductor set 804. Conductorset 804 includes two insulated conductors 806 that extend along a lengthof the cable 802. Cable 802 may include multiple conductor sets 804spaced apart from each other across the width of the cable 802. Twoshielding films 808 are disposed on opposite sides of the cable 802. Intransverse cross section, cover portions 807 of the shielding films 808,in combination, substantially surround the conductor set 804 in thecover region 814 of the cable 802. For example, the cover portions ofthe first and second shielding films in combination substantiallysurround each conductor set by encompassing at least 70% of a peripheryof each conductor set. Pinched portions 809 of the shielding films 808form pinched regions 818 of the cable 802 on each side of the conductorset 804.

Shielding films 808 may include optional adhesive layers 810 a, 810 bthat bond the pinched portions 809 of the shielding films 808 to eachother in the pinched regions 818 of the cable 802. Adhesive layer 810 ais disposed on one of the non-conductive polymeric layers 808 b andadhesive layer 810 b is disposed on another of the non-conductivepolymeric layers 808 b. The adhesive layers 810 a, 810 b may or may notbe present in the cover region 814 of the cable 802. If present, theadhesive layers 810 a, 810 b may extend fully or partially across thewidth of the cover portions 807 of the shielding film 808, bonding thecover portions 807 of the shielding films 808 to the insulatedconductors 806.

In this example, insulated conductors 806 and shielding films 808 arearranged generally in a single plane and effectively in a twinaxialconfiguration which may be used in a single ended circuit arrangement ora differential pair circuit arrangement. Shielding films 808 include aconductive layer 808 a and a non-conductive polymeric layer 808 b.Non-conductive polymeric layer 808 b faces insulated conductors 806.Conductive layer 808 a may be deposited onto non-conductive polymericlayer 808 b using any suitable method.

FIG. 7 b is a cross sectional view across a width shielded electricalcable 902 that shows a single conductor set 904. Conductor set 904includes two insulated conductors 906 that extend along a length of thecable 902. Cable 902 may include multiple conductor sets 904 spacedapart from each other along a width of the cable 902 and extending alonga length of the cable 902. Two shielding films 908 are disposed onopposite sides of the cable 902. In transverse cross section, coverportions 907 of the shielding films 908, in combination, substantiallysurround the conductor set 904 in the cover regions 914 of the cable902. Pinched portions 909 of the shielding films 908 form pinchedregions 918 of the cable 902 on each side of the conductor set 904.

One or more optional adhesive layers 910 a, 910 b bond the pinchedportions 909 of the shielding films 908 to each other in the pinchedregions 918 on both sides of conductor set 904. The adhesive layers 910a, 910 b may extend fully or partially across the width of the coverportions 907 of the shielding film 908. Insulated conductors 906 arearranged generally in a single plane and effectively form a twinaxialcable configuration and can be used in a single ended circuitarrangement or a differential pair circuit arrangement. Shielding films908 include a conductive layer 908 a and a non-conductive polymericlayer 908 b. Conductive layer 908 a faces insulated conductors 906.Conductive layer 908 a may be deposited onto non-conductive polymericlayer 908 b using any suitable method.

FIG. 7 c is a cross sectional view across a width of a shieldedelectrical cable 1002 showing a single conductor set 1004. Conductor set1004 includes two insulated conductors 1006 that extend along a lengthof the cable 1002. Cable 1002 may include multiple conductor sets 1004spaced apart from each other along a width of the cable 1002 andextending along a length of the cable 1002. Two shielding films 1008 aredisposed on opposite sides of the cable 1002 and include cover portions1007. In transverse cross section, the cover portions 1007, incombination, substantially surround the conductor set 1004 in a coverregion 1014 of the cable 1002. Pinched portions 1009 of the shieldingfilms 1008 form pinched regions 1018 of the cable 1002 on each side ofthe conductor set 1004.

Shielding films 1008 include one or more optional adhesive layers 1010a, 1010 b that bond the pinched portions 1009 of the shielding films1008 to each other on both sides of conductor set 1004 in the pinchedregions 1018. The adhesive layers 1010 a, 1010 b may extend fully orpartially across the width of the cover portions 1007 of the shieldingfilm 1008. Insulated conductors 1006 are arranged generally in a singleplane and effectively in a twinaxial cable configuration that can beused in a single ended circuit arrangement or a differential paircircuit arrangement. Shielding films 1008 include a stand-aloneconductive film.

FIG. 7 d is a cross sectional view of a shielded electrical cable 1102that shows a single conductor set 1104. Conductor set 1104 includes twoinsulated conductors 1106 with extend along a length of the cable 1102.Cable 1102 may include multiple conductor sets 1104 spaced apart fromeach other along a width of the cable 1102 and extending along a lengthof the cable 1102. Two shielding films 1108 are disposed on oppositesides of the cable 1102 and include cover portions 1107. In transversecross section, the cover portions 1107, in combination, substantiallysurround conductor set 1104 in a cover region 1114 of the cable 1102.Pinched portions 1109 of the shielding films 1108 form pinched regions1118 of the cable 1102 on each side of the conductor set 1104.

Shielding films 1108 include one or more optional adhesive layers 1110that bond the pinched portions 1109 of the shielding films 1108 to eachother in the pinched regions 1118 on both sides of conductor set 1104.The adhesive layer 1010 a, 1010 b may extend fully or partially acrossthe width of the cover portions 1107 of the shielding film 1108.

Insulated conductors 1106 are arranged generally in a single plane andeffectively in a twinaxial cable configuration. The twinaxial cableconfiguration can be used in a single ended circuit arrangement or adifferential circuit arrangement. Shielding films 1108 include aconductive layer 1108 a, a non-conductive polymeric layer 1108 b, and alaminating adhesive layer 1108 c disposed between conductive layer 1108a and non-conductive polymeric layer 1108 b, thereby laminatingconductive layer 1108 a to non-conductive polymeric layer 1108 b.Conductive layer 1108 a faces insulated conductors 1106.

As discussed elsewhere herein, adhesive material may be used in thecable construction to bond one or two shielding films to one, some, orall of the conductor sets at cover regions of the cable, and/or adhesivematerial may be used to bond two shielding films together at pinchedregions of the cable. A layer of adhesive material may be disposed on atleast one shielding film, and in cases where two shielding films areused on opposite sides of the cable, a layer of adhesive material may bedisposed on both shielding films. In the latter cases, the adhesive usedon one shielding film is preferably the same as, but may if desired bedifferent from, the adhesive used on the other shielding film. A givenadhesive layer may include an electrically insulative adhesive, and mayprovide an insulative bond between two shielding films. Furthermore, agiven adhesive layer may provide an insulative bond between at least oneof shielding films and insulated conductors of one, some, or all of theconductor sets, and between at least one of shielding films and one,some, or all of the ground conductors (if any). Alternatively, a givenadhesive layer may include an electrically conductive adhesive, and mayprovide a conductive bond between two shielding films. Furthermore, agiven adhesive layer may provide a conductive bond between at least oneof shielding films and one, some, or all of the ground conductors (ifany). Suitable conductive adhesives include conductive particles toprovide the flow of electrical current. The conductive particles can beany of the types of particles currently used, such as spheres, flakes,rods, cubes, amorphous, or other particle shapes. They may be solid orsubstantially solid particles such as carbon black, carbon fibers,nickel spheres, nickel coated copper spheres, metal-coated oxides,metal-coated polymer fibers, or other similar conductive particles.These conductive particles can be made from electrically insulatingmaterials that are plated or coated with a conductive material such assilver, aluminum, nickel, or indium tin-oxide. The metal-coatedinsulating material can be substantially hollow particles such as hollowglass spheres, or may comprise solid materials such as glass beads ormetal oxides. The conductive particles may be on the order of severaltens of microns to nanometer sized materials such as carbon nanotubes.Suitable conductive adhesives may also include a conductive polymericmatrix.

When used in a given cable construction, an adhesive layer is preferablysubstantially conformable in shape relative to other elements of thecable, and conformable with regard to bending motions of the cable. Insome cases, a given adhesive layer may be substantially continuous,e.g., extending along substantially the entire length and width of agiven major surface of a given shielding film. In some cases, theadhesive layer may include be substantially discontinuous. For example,the adhesive layer may be present only in some portions along the lengthor width of a given shielding film. A discontinuous adhesive layer mayfor example include a plurality of longitudinal adhesive stripes thatare disposed, e.g., between the pinched portions of the shielding filmson both sides of each conductor set and between the shielding filmsbeside the ground conductors (if any). A given adhesive material may beor include at least one of a pressure sensitive adhesive, a hot meltadhesive, a thermoset adhesive, and a curable adhesive. An adhesivelayer may be configured to provide a bond between shielding films thatis substantially stronger than a bond between one or more insulatedconductor and the shielding films. This may be achieved, e.g., byappropriate selection of the adhesive formulation. An advantage of thisadhesive configuration is to allow the shielding films to be readilystrippable from the insulation of insulated conductors. In other cases,an adhesive layer may be configured to provide a bond between shieldingfilms and a bond between one or more insulated conductor and theshielding films that are substantially equally strong. An advantage ofthis adhesive configuration is that the insulated conductors areanchored between the shielding films. When a shielded electrical cablehaving this construction is bent, this allows for little relativemovement and therefore reduces the likelihood of buckling of theshielding films. Suitable bond strengths may be chosen based on theintended application. In some cases, a conformable adhesive layer may beused that has a thickness of less than about 0.13 mm. In exemplaryembodiments, the adhesive layer has a thickness of less than about 0.05mm.

A given adhesive layer may conform to achieve desired mechanical andelectrical performance characteristics of the shielded electrical cable.For example, the adhesive layer may conform to be thinner between theshielding films in areas between conductor sets, which increases atleast the lateral flexibility of the shielded cable. This may allow theshielded cable to be placed more easily into a curvilinear outer jacket.In some cases, an adhesive layer may conform to be thicker in areasimmediately adjacent the conductor sets and substantially conform to theconductor sets. This may increase the mechanical strength and enableforming a curvilinear shape of shielding films in these areas, which mayincrease the durability of the shielded cable, for example, duringflexing of the cable. In addition, this may help to maintain theposition and spacing of the insulated conductors relative to theshielding films along the length of the shielded cable, which may resultin more uniform impedance and superior signal integrity of the shieldedcable.

A given adhesive layer may conform to effectively be partially orcompletely removed between the shielding films in areas betweenconductor sets, e.g., in pinched regions of the cable. As a result, theshielding films may electrically contact each other in these areas,which may increase the electrical performance of the cable. In somecases, an adhesive layer may conform to effectively be partially orcompletely removed between at least one of the shielding films and theground conductors. As a result, the ground conductors may electricallycontact at least one of shielding films in these areas, which mayincrease the electrical performance of the cable. Even in cases where athin layer of adhesive remains between at least one of shielding filmsand a given ground conductor, asperities on the ground conductor maybreak through the thin adhesive layer to establish direct electricalcontact as intended.

FIGS. 8 a-8 c are cross sectional views of three exemplary embodimentsof a shielded electrical cable which illustrate examples of theplacement of ground conductors in the shielded electrical cables. Anaspect of a shielded electrical cable is proper grounding of the shieldand such grounding can be accomplished in a number of ways. In somecases, a given ground conductor can electrically contact at least one ofthe shielding films such that grounding the given ground conductor alsogrounds the shielding films. Such a ground conductor may also bereferred to as a “drain wire”. Electrical contact between the shieldingfilm and the ground conductor may be characterized by a relatively lowDC resistance, e.g., a DC resistance of less than 10 ohms, or less than2 ohms, or of substantially 0 ohms. In some cases, a given groundconductor does not electrically contact the shielding films, but may bean individual element in the cable construction that is independentlyterminated to any suitable individual contact element of any suitabletermination component, such as, e.g., a conductive path or other contactelement on a printed circuit board, paddle board, or other device. Sucha ground conductor may also be referred to as a “ground wire”. FIG. 8 aillustrates an exemplary shielded electrical cable in which groundconductors are positioned external to the shielding films. FIGS. 8 b-8 cillustrate embodiments in which the ground conductors are positionedbetween the shielding films, and may be included in the conductor set.One or more ground conductors may be placed in any suitable positionexternal to the shielding films, between the shielding films, or acombination of both.

Referring to FIG. 8 a, a shielded electrical cable 1202 includes asingle conductor set 1204 that extends along a length of the cable 1202.Conductor set 1204 includes two insulated conductors 1206, i.e., onepair of insulated conductors. Cable 1202 may include multiple conductorsets 1204 spaced apart from each other across a width of the cable andextending along a length of the cable 1202. Two shielding films 1208disposed on opposite sides of the cable 1202 include cover portions1207. In transverse cross section, the cover portions 1207, incombination, substantially surround conductor set 1204. An optionaladhesive layer 1210 is disposed between pinched portions 1209 of theshielding films 1208 and bonds shielding films 1208 to each other onboth sides of conductor set 1204. Insulated conductors 1206 are arrangedgenerally in a single plane and effectively in a twinaxial cableconfiguration that can be used in a single ended circuit arrangement ora differential pair circuit arrangement. Shielded electrical cable 1202further includes a plurality of ground conductors 1212 positionedexternal to shielding films 1208. Ground conductors 1212 are placedover, under, and on both sides of conductor set 1204. Optionally,shielded electrical cable 1202 includes protective films 1220surrounding shielding films 1208 and ground conductors 1212. Protectivefilms 1220 include a protective layer 1220 a and an adhesive layer 1220b bonding protective layer 1220 a to shielding films 1208 and groundconductors 1212. Alternatively, shielding films 1208 and groundconductors 1212 may be surrounded by an outer conductive shield, suchas, e.g., a conductive braid, and an outer insulative jacket (notshown).

Referring to FIG. 8 b, shielded electrical cable 1302 includes a singleconductor set 1304 that extends along a length of cable 1302. Conductorset 1304 includes two insulated conductors 1306. Cable 1302 may includemultiple conductor sets 1304 spaced apart from each other across a widthof the cable 1302 and extending along the length of the cable 1302. Twoshielding films 1308 are disposed on opposite sides of the cable 1302and include cover portions 1307. In transverse cross section, coverportions, in combination, substantially surround conductor set 1304. Anoptional adhesive layer 1310 is disposed between pinched portions 1309of the shielding films 1308 and bonds shielding films 1308 to each otheron both sides of conductor set 1304. Insulated conductors 1306 arearranged generally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement. Shielded electrical cable 1302further includes a plurality of ground conductors 1312 positionedbetween shielding films 1308. Two of the ground conductors 1312 areincluded in conductor set 1304, and two of the ground conductors 1312are spaced apart from conductor set 1304.

Referring to FIG. 8 c, shielded electrical cable 1402 includes a singleconductor set 1404 that extends along a length of cable 1402. Conductorset 1404 includes two insulated conductors 1406. Cable 1402 may includemultiple conductor sets 1304 spaced apart from each other across a widthof the cable 1402 and extending along the length of the cable 1402. Twoshielding films 1408 are disposed on opposite sides of the cable 1402and include cover portions 1407. In transverse cross section, the coverportions 1407, in combination, substantially surround conductor set1404. An optional adhesive layer 1410 is disposed between pinchedportions 1409 of the shielding films 1408 and bonds shielding films 1408to each other on both sides of conductor set 1404. Insulated conductors1406 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielded electricalcable 1402 further includes a plurality of ground conductors 1412positioned between shielding films 1408. All of the ground conductors1412 are included in conductor set 1404. Two of the ground conductors1412 and insulated conductors 1406 are arranged generally in a singleplane.

FIGS. 9 a-9 b illustrate an electrical assembly 1500 including a cable1502 terminated to a printed circuit board 1514. Electrical assembly1500 includes a shielded electrical cable 1502 and an electricallyconductive cable clip 1522. Shielded electrical cable 1502 includes aplurality of spaced apart conductor sets 1504 arranged generally in asingle plane. Each conductor set 1504 includes two insulated conductors1506 that extend along a length of the cable 1502. Two shielding films1508 are disposed on opposite sides of the cable 1502 and, in transversecross section, substantially surround conductor sets 1504. One or moreoptional adhesive layers 1510 are disposed between shielding films 1508and bond shielding films 1508 to each other on both sides of eachconductor set 1504.

Cable clip 1522 is clamped or otherwise attached to an end portion ofshielded electrical cable 1502 such that at least one of shielding films1508 electrically contacts cable clip 1522. Cable clip 1522 isconfigured for termination to a ground reference, such as, e.g., contactelement 1516 on printed circuit board 1514, to establish a groundconnection between shielded electrical cable 1502 and the groundreference. Cable clip may be terminated to the ground reference usingany suitable method, including soldering, welding, crimping, mechanicalclamping, and adhesively bonding, to name a few. When terminated, cableclip 1522 may facilitate termination of the end portions of theconductors of insulated conductors 1506 of shielded electrical cable1502 to contact elements of a termination point, such as, e.g., contactelements 1516 on printed circuit board 1514. Shielded electrical cable1502 may include one or more ground conductors as described herein thatmay electrically contact cable clip 1522 in addition to or instead of atleast one of shielding films 1508.

FIGS. 10 a-10 g illustrate an exemplary method of making a shieldedelectrical cable that may be substantially the same as that shown inFIG. 1.

In the step illustrated in FIG. 10 a, insulated conductors 6 are formedusing any suitable method, such as, e.g., extrusion, or are otherwiseprovided. Insulated conductors 6 may be formed of any suitable length.Insulated conductors 6 may then be provided as such or cut to a desiredlength. Ground conductors 12 (see FIG. 10 c) may be formed and providedin a similar fashion.

In the step illustrated in FIG. 10 b, one or more shielding films 8 areformed. A single layer or multilayer web may be formed using anysuitable method, such as, e.g., continuous wide web processing. Eachshielding film 8 may be formed of any suitable length. The shieldingfilm 8 may then be provided as such or cut to a desired length and/orwidth. The shielding film 8 may be pre-formed to have transverse partialfolds to increase flexibility in the longitudinal direction. One or bothof the shielding films 8 may include a conformable adhesive layer 10,which may be formed on the shielding film 8 using any suitable method,such as, e.g., laminating or sputtering.

In the step illustrated in FIG. 10 c, a plurality of insulatedconductors 6, ground conductors 12, and shielding films 8 are provided.A forming tool 24 is provided. Forming tool 24 includes a pair offorming rolls 26 a, 26 b having a shape corresponding to a desiredcross-sectional shape of the shielded electrical cable 2, the formingtool also including a bite 28. Insulated conductors 6, ground conductors12, and shielding films 8 are arranged according to the configuration ofdesired shielded electrical cable 2, such as any of the cables shownand/or described herein, and positioned in proximity to forming rolls 26a, 26 b, after which they are concurrently fed into bite 28 of formingrolls 26 a, 26 b and disposed between forming rolls 26 a, 26 b. Formingtool 24 forms shielding films 8 around conductor sets 4 and groundconductor 12 and bonds shielding films 8 to each other on both sides ofeach conductor set 4 and ground conductors 12. Heat may be applied tofacilitate bonding. Although in this embodiment, forming shielding films8 around conductor sets 4 and ground conductor 12 and bonding shieldingfilms 8 to each other on both sides of each conductor set 4 and groundconductors 12 occur in a single operation, in other embodiments, thesesteps may occur in separate operations.

FIG. 10 d illustrates shielded electrical cable 2 as it is formed byforming tool 24. In the optional step illustrated in FIG. 10 e,longitudinal splits 18 are formed between conductor sets 4. Splits 18may be formed in shielded electrical cable 2 using any suitable method,such as, e.g., laser cutting or punching.

In another optional step illustrated in FIG. 10 f, shielding films 8 ofshielded electrical cable 2 may be folded lengthwise along the pinchedregions multiple times into a bundle, and an outer conductive shield 30may be provided around the folded bundle using any suitable method. Anouter jacket 32 may also be provided around outer conductive shield 30using any suitable method, such as, e.g., extrusion. In someembodiments, the outer conductive shield 30 may be omitted and the outerjacket 32 may be provided around the folded shielded cable.

FIGS. 11 a-11 c illustrate a detail of an exemplary method of making ashielded electrical cable. FIGS. 11 a-11 c illustrate how one or moreadhesive layers may be conformably shaped during the forming and bondingof the shielding films.

In the step illustrated in FIG. 11 a, an insulated conductor 1606, aground conductor 1612 spaced apart from insulated conductor 1606, andtwo shielding films 1608 are provided. Shielding films 1608 each includea conformable adhesive layer 1610. In the steps illustrated in FIGS. 11b-11 c, shielding films 1608 are formed around insulated conductor 1606and ground conductor 1612 and bonded to each other. Initially, asillustrated in FIG. 11 b, adhesive layers 1610 still have their originalthickness. As the forming and bonding of shielding films 1608 proceeds,conformable adhesive layers 1610 conform to achieve desired mechanicaland electrical performance characteristics of shielded electrical cable1602 (FIG. 11 c).

As illustrated in FIG. 11 c, adhesive layers 1610 conform to be thinnerbetween shielding films 1608 on both sides of insulated conductor 1606and ground conductor 1612; a portion of adhesive layers 1610 displacesaway from these areas. Further, conformable adhesive layers 1610 conformto be thicker in areas immediately adjacent insulated conductor 1606 andground conductor 1612, and substantially conform to insulated conductor1606 and ground conductor 1612; a portion of adhesive layers 1610displaces into these areas. Further, conformable adhesive layers 1610conform to effectively be removed between shielding films 1608 andground conductor 1612; conformable adhesive layers 1610 displace awayfrom these areas such that ground conductor 1612 electrically contactsshielding films 1608.

In some approaches, a semi-rigid cable can be formed using a thickermetal or metallic material as a shielding layer. For example, aluminumor other metal may be used in this approach without a backing film. Thealuminum (or other material) is passed through shaping dies to createcorrugations or channels in the aluminum which form cover portions andpinched portions of the shield. The insulated conductors are placed inthe corrugations that form the cover portions. If drain wires are used,corrugations may also be formed for the drain wires. The insulatedconductors and, optionally, drain wires, are sandwiched in betweenopposite layers of corrugated aluminum. The aluminum layers may bebonded together with adhesive, or welded, for example; Connectionbetween the upper and lower corrugated aluminum shielding films could bethrough un-insulated drain wires. Alternatively, the pinched portions ofthe aluminum could be embossed, pinched further and/or punched throughto provide positive contact between the corrugated shielding layers.

In exemplary embodiments, the cover regions of the shielded electricalcable include concentric regions and transition regions positioned onone or both sides of a given conductor set. Portions of a givenshielding film in the concentric regions are referred to as concentricportions of the shielding film and portions of the shielding film in thetransition regions are referred to as transition portions of theshielding film. The transition regions can be configured to provide highmanufacturability and strain and stress relief of the shieldedelectrical cable. Maintaining the transition regions at a substantiallyconstant configuration (including aspects such as, e.g., size, shape,content, and radius of curvature) along the length of the shieldedelectrical cable may help the shielded electrical cable to havesubstantially uniform electrical properties, such as, e.g., highfrequency isolation, impedance, skew, insertion loss, reflection, modeconversion, eye opening, and jitter.

Additionally, in certain embodiments, such as, e.g., embodiments whereinthe conductor set includes two insulated conductors that extend along alength of the cable that are arranged generally in a single andeffectively as a twinaxial cable that can be connected in a differentialpair circuit arrangement, maintaining the transition portion at asubstantially constant configuration along the length of the shieldedelectrical cable can beneficially provide substantially the sameelectromagnetic field deviation from an ideal concentric case for bothconductors in the conductor set. Thus, careful control of theconfiguration of this transition portion along the length of theshielded electrical cable can contribute to the advantageous electricalperformance and characteristics of the cable. FIGS. 12 a-14 b illustratevarious exemplary embodiments of a shielded electrical cable thatinclude transition regions of the shielding films disposed on one orboth sides of the conductor set.

The shielded electrical cable 1702, which is shown in cross section inFIGS. 12 a and 12 b, includes a single conductor set 1704 that extendsalong a length of the cable 1702. The shielded electrical cable 1702 maybe made to have multiple conductor sets 1704 spaced apart from eachother along a width of the cable 1702 and extending along a length ofthe cable 1702. Although only one insulated conductor 1706 is shown inFIG. 12 a, multiple insulated conductors may be included in theconductor set 1704, if desired.

The insulated conductor of a conductor set that is positioned nearest toa pinched region of the cable is considered to be an end conductor ofthe conductor set. The conductor set 1704, as shown, has a singleinsulated conductor 1706 and it is also an end conductor, since it ispositioned nearest to the pinched region 1718 of the shielded electricalcable 1702.

First and second shielding films 1708 are disposed on opposite sides ofthe cable and include cover portions 1707. In transverse cross section,the cover portions 1707 substantially surround conductor set 1704. Anoptional adhesive layer 1710 is disposed between the pinched portions1709 of the shielding films 1708 and bonds shielding films 1708 to eachother in the pinched regions 1718 of the cable 1702 on both sides ofconductor set 1704. The optional adhesive layer 1710 may extendpartially or fully across the cover portion 1707 of the shielding films1708, e.g., from the pinched portion 1709 of the shielding film 1708 onone side of the conductor set 1704 to the pinched portion 1709 of theshielding film 1708 on the other side of the conductor set 1704.

Insulated conductor 1706 is effectively arranged as a coaxial cablewhich may be used in a single ended circuit arrangement. Shielding films1708 may include a conductive layer 1708 a and a non-conductivepolymeric layer 1708 b. In some embodiments, as illustrated by FIGS. 12a and 12 b, the conductive layer 1708 a faces the insulated conductors.Alternatively, the orientation of the conductive layers of one or bothof shielding films 1708 may be reversed, as discussed elsewhere herein.

Shielding films 1708 include a concentric portion that is substantiallyconcentric with the end conductor 1706 of the conductor set 1704. Theshielded electrical cable 1702 includes transition regions 1736.Portions of the shielding film 1708 in the transition region 1736 of thecable 1702 are transition portions 1734 of the shielding films 1708. Insome embodiments, shielded electrical cable 1702 includes a transitionregions 1736 positioned on both sides of the conductor set 1704 and insome embodiments, the transition regions 1736 may be positioned on onlyone side of conductor set 1704.

Transition regions 1736 are defined by shielding films 1708 andconductor set 1704. The transition portions 1734 of the shielding films1708 in the transition regions 1736 provide a gradual transition betweenconcentric portions 1711 and pinched portions 1709 of the shieldingfilms 1708. As opposed to a sharp transition, such as, e.g., aright-angle transition or a transition point (as opposed to a transitionportion), a gradual or smooth transition, such as, e.g., a substantiallysigmoidal transition, provides strain and stress relief for shieldingfilms 1708 in transition regions 1736 and prevents damage to shieldingfilms 1708 when shielded electrical cable 1702 is in use, e.g., whenlaterally or axially bending shielded electrical cable 1702. This damagemay include, e.g., fractures in conductive layer 1708 a and/or debondingbetween conductive layer 1708 a and non-conductive polymeric layer 1708b. In addition, a gradual transition prevents damage to shielding films1708 in manufacturing of shielded electrical cable 1702, which mayinclude, e.g., cracking or shearing of conductive layer 1708 a and/ornon-conductive polymeric layer 1708 b. Use of the disclosed transitionregions on one or both sides of one, some or all of the conductor setsin a shielded electrical ribbon cable represents a departure fromconventional cable configurations, such as, e.g., an typical coaxialcable, wherein a shield is generally continuously disposed around asingle insulated conductor, or a typical conventional twinaxial cable,in which a shield is continuously disposed around a pair of insulatedconductors.

According to one aspect of at least some of the disclosed shieldedelectrical cables, acceptable electrical properties can be achieved byreducing the electrical impact of the transition region, e.g., byreducing the size of the transition region and/or carefully controllingthe configuration of the transition region along the length of theshielded electrical cable. Reducing the size of the transition regionreduces the capacitance deviation and reduces the required space betweenmultiple conductor sets, thereby reducing the conductor set pitch and/orincreasing the electrical isolation between conductor sets. Carefulcontrol of the configuration of the transition region along the lengthof the shielded electrical cable contributes to obtaining predictableelectrical behavior and consistency, which provides for high speedtransmission lines so that electrical data can be more reliablytransmitted. Careful control of the configuration of the transitionregion along the length of the shielded electrical cable is a factor asthe size of the transition portion approaches a lower size limit.

An electrical characteristic that is often considered is thecharacteristic impedance of the transmission line. Any impedance changesalong the length of a transmission line may cause power to be reflectedback to the source instead of being transmitted to the target. Ideally,the transmission line will have no impedance variation along its length,but, depending on the intended application, variations up to 5-10% maybe acceptable. Another electrical characteristic that is oftenconsidered in twinaxial cables (differentially driven) is skew orunequal transmission speeds of two transmission lines of a pair along atleast a portion of their length. Skew produces conversion of thedifferential signal to a common mode signal that can be reflected backto the source, reduces the transmitted signal strength, createselectromagnetic radiation, and can dramatically increase the bit errorrate, in particular jitter. Ideally, a pair of transmission lines willhave no skew, but, depending on the intended application, a differentialS-parameter SCD21 or SCD12 value (representing the differential-tocommon mode conversion from one end of the transmission line to theother) of less than −25 to −30 dB up to a frequency of interest, suchas, e.g., 6 GHz, may be acceptable. Alternatively, skew can be measuredin the time domain and compared to a required specification. Shieldedelectrical cables described herein may achieve skew values of less thanabout 20 picoseconds/meter (psec/m) or less than about 10 psec/m, forexample at data transfer speeds of up to 10 Gbps.

Referring again to FIGS. 12 a-12 b, in part to help achieve acceptableelectrical properties, transition regions 1736 of shielded electricalcable 1702 may each include a cross-sectional transition area 1764 a.The transition area 1764 a is smaller than a cross-sectional area 1706 aof conductor 1706. As best shown in FIG. 12 b, cross-sectionaltransition area 1736 a of transition region 1736 is defined bytransition points 1734′ and 1734″.

The transition points 1734′ occur where the shielding films deviate frombeing substantially concentric with the end insulated conductor 1706 ofthe conductor set 1704. The transition points 1734′ are the points ofinflection of the shielding films 1708 at which the curvature of theshielding films 1708 changes sign. For example, with reference to FIG.12 b, the curvature of the upper shielding film 1708 transitions fromconcave downward to concave upward at the inflection point which is theupper transition point 1734′. The curvature of the lower shielding film1708 transitions from concave upward to concave downward at the lowerinflection point which is the transition point 1734′. The othertransition points 1734″ occur where a separation between the pinchedportions 1709 of the shielding films 1708 exceeds the minimumseparation, d₁, of the pinched portions 1709, by a predetermined factor,e.g, within a range of about 1.2 to about 1.5, for example.

In addition, each transition area 1736 a may include a void area 1736 b.Void areas 1736 b on either side of the conductor set 1704 may besubstantially the same. Further, adhesive layer 1710 may have athickness T_(ac) at the concentric portion 1711 of the shielding film1708, and a thickness at the transition portion 1734 of the shieldingfilm 1708 that is greater than thickness T_(ac). Similarly, adhesivelayer 1710 may have a thickness T_(ap) between the pinched portions 1709of the shielding films 1708, and a thickness at the transition portion1734 of the shielding film 1708 that is greater than thickness T_(ap).Adhesive layer 1710 may represent at least 25% of cross-sectionaltransition area 1736 a. The presence of adhesive layer 1710 intransition area 1736 a, in particular at a thickness that is greaterthan thickness T_(ac) or thickness T_(ap), contributes to the strengthof the cable 1702 in the transition region 1736.

Careful control of the manufacturing process and the materialcharacteristics of the various elements of shielded electrical cable1702 may reduce variations in void area 1736 b and the thickness ofconformable adhesive layer 1710 in transition region 1736, which may inturn reduce variations in the capacitance of cross-sectional transitionarea 1736 a. Shielded electrical cable 1702 may include transitionregion 1736 positioned on one or both sides of conductor set 1704 thatincludes a cross-sectional transition area 1736 a that is substantiallyequal to or smaller than a cross-sectional area 1706 a of conductor1706. Shielded electrical cable 1702 may include a transition region1736 positioned on one or both sides of conductor set 1704 that includesa cross-sectional transition area 1736 a that is substantially the samealong the length of conductor 1706. For example, cross-sectionaltransition area 1736 a may vary less than 50% over a length of 1 meter.Shielded electrical cable 1702 may include transition regions 1736positioned on both sides of conductor set 1704 that each include across-sectional transition area, wherein the sum of cross-sectionalareas 1734 a is substantially the same along the length of conductor1706. For example, the sum of cross-sectional areas 1734 a may vary lessthan 50% over a length of 1 meter. Shielded electrical cable 1702 mayinclude transition regions 1736 positioned on both sides of conductorset 1704 that each include a cross-sectional transition area 1736 a,wherein the cross-sectional transition areas 1736 a are substantiallythe same. Shielded electrical cable 1702 may include transition regions1736 positioned on both sides of conductor set 1704, wherein thetransition regions 1736 are substantially identical. Insulated conductor1706 has an insulation thickness T₁, and transition region 1736 may havea lateral length L_(t) that is less than insulation thickness T₁. Thecentral conductor of insulated conductor 1706 has a diameter D_(c), andtransition region 1736 may have a lateral length L_(t) that is less thanthe diameter D_(c). The various configurations described above mayprovide a characteristic impedance that remains within a desired range,such as, e.g., within 5-10% of a target impedance value, such as, e.g.,50 Ohms, over a given length, such as, e.g., 1 meter.

Factors that can influence the configuration of transition region 1736along the length of shielded electrical cable 1702 include themanufacturing process, the thickness of conductive layers 1708 a andnon-conductive polymeric layers 1708 b, adhesive layer 1710, and thebond strength between insulated conductor 1706 and shielding films 1708,to name a few.

In one aspect, conductor set 1704, shielding films 1708, and transitionregion 1736 are cooperatively configured in an impedance controllingrelationship. An impedance controlling relationship means that conductorset 1704, shielding films 1708, and transition region 1736 arecooperatively configured to control the characteristic impedance of theshielded electrical cable.

FIGS. 13 a-13 b illustrate, in transverse cross section, two exemplaryembodiments of a shielded electrical cable which has two insulatedconductors in a conductor set. Referring to FIG. 13 a, shieldedelectrical cable 1802 includes a single conductor set 1804 including twoindividually insulated conductors 1806 extending along a length of thecable 1802. Two shielding films 1808 are disposed on opposite sides ofthe cable 1802 and in combination substantially surround conductor set1804. An optional adhesive layer 1810 is disposed between pinchedportions 1809 of the shielding films 1808 and bonds shielding films 1808to each other on both sides of conductor set 1804 in the pinched regions1818 of the cable 1802. Insulated conductors 1806 can be arrangedgenerally in a single plane and effectively in a twinaxial cableconfiguration. The twinaxial cable configuration can be used in adifferential pair circuit arrangement or in a single ended circuitarrangement. Shielding films 1808 may include a conductive layer 1808 aand a non-conductive polymeric layer 1808 b or may include theconductive layer 1808 a without the non-conductive polymeric layer 1808b. FIG. 13 a shows conductive layer 1808 a facing insulated conductors1806, but in alternative embodiments, one or both of the shielding filmsmay have a reversed orientation.

The cover portion 1807 of at least one of the shielding films 1808includes concentric portions 1811 that are substantially concentric withcorresponding end conductors 1806 of the conductor set 1804. In thetransition region 1836 of the cable 1802, transition portion 1834 of theshielding films 1808 are between the concentric portions 1811 and thepinched portions 1809 of the shielding films 1808. Transition portions1836 are positioned on both sides of conductor set 1804 and each suchportion includes a cross-sectional transition area 1836 a. The sum ofcross-sectional transition areas 1836 a is preferably substantially thesame along the length of conductors 1806. For example, the sum ofcross-sectional areas 1834 a may vary less than 50% over a length of 1meter.

In addition, the two cross-sectional transition areas 1834 a may besubstantially the same and/or substantially identical. Thisconfiguration of transition regions contributes to a characteristicimpedance for each conductor 1806 (single-ended) and a differentialimpedance that both remain within a desired range, such as, e.g., within5-10% of a target impedance value over a given length, such as, e.g., 1meter. In addition, this configuration of transition region 1836 mayminimize skew of the two conductors 1806 along at least a portion oftheir length.

When the cable is in an unfolded, planar configuration, each of theshielding films may be characterizable in transverse cross section by aradius of curvature that changes across a width of the cable 1802. Themaximum radius of curvature of the shielding film 1808 may occur, forexample, at the pinched portion 1809 of the cable 1802 or near thecenter point of the cover portion 1807 of the multi-conductor cable set1804 illustrated in FIG. 13 a. At these positions, the film may besubstantially flat and the radius of curvature may be substantiallyinfinite. The minimum radius of curvature of the shielding film 1808 mayoccur, for example, at the transition portion 1834 of the shielding film1808. In some embodiments, the radius of curvature of the shielding filmacross the width of the cable is at least about 50 micrometers, i.e.,the radius of curvature does not have a magnitude smaller than 50micrometers at any point along the width of the cable, between the edgesof the cable. In some embodiments, for shielding films that include atransition portion, the radius of curvature of the transition portion ofthe shielding film is similarly at least about 50 micrometers.

In an unfolded, planar configuration, shielding films 1808 that includea concentric portion and a transition portion are characterizable by aradius of curvature of the concentric portion, R₁, and/or a radius ofcurvature of the transition portion r₁, which are illustrated in FIG. 13a. In some embodiments, R₁/r₁ is in a range of 2 to 15.

Referring to FIG. 13 b, shielded electrical cable 1902 is similar insome aspects to shielded electrical cable 1802. Whereas shieldedelectrical cable 1802 has individually insulated conductors 1806,shielded electrical cable 1902 has jointly insulated conductors 1906.Nonetheless, transition regions 1936 are substantially similar totransition regions 1836 and provide the same benefits to shieldedelectrical cable 1902.

FIGS. 14 a-14 b illustrate variations in position and configuration ofthe transition portions. In these exemplary embodiments, the shieldingfilms 2008, 2108 have an asymmetric configuration which changes theposition of the transition portions relative to more symmetricembodiment such that of FIG. 13 a. Shielded electrical cables 2002 (FIG.14 a) and 2102 (FIG. 14 b) have pinched portions 2009 of shielding films2008, 2108 lie in a plane that is offset from the plane of symmetry ofthe insulated conductors 2006, 2106. As a result, the transition regions2036, 2136 have a somewhat offset position and configuration relative toother depicted embodiments. However, by ensuring that the transitionregions 2036, 2136 are positioned substantially symmetrically withrespect to corresponding insulated conductors 2006, 2106 (e.g., withrespect to a vertical plane between the conductors 2006, 2106), and thatthe configuration of transition regions 2036, 2136 is carefullycontrolled along the length of shielded electrical cables 2002, 2102,shielded electrical cables 2002, 2102 can be configured to still provideacceptable electrical properties.

FIGS. 15 a-15 c, 18 and 19 illustrate additional exemplary embodimentsof shielded electrical cables. FIGS. 16 a-16 g, 17 a-17 b and 20 a-20 fillustrate several exemplary embodiments of a pinched portion of ashielded electrical cable. FIGS. 15 a-20 f illustrate examples of apinched portion that is configured to electrically isolate a conductorset of the shielded electrical cable. The conductor set may beelectrically isolated from an adjacent conductor set (e.g., to minimizecrosstalk between adjacent conductor sets, FIGS. 15 a-15 c and 16 a-16g) or from the external environment of the shielded electrical cable(e.g., to minimize electromagnetic radiation escape from the shieldedelectrical cable and minimize electromagnetic interference from externalsources, FIGS. 19 and 20 a-20 f). In both cases, the pinched portion mayinclude various mechanical structures to change the electricalisolation. Examples include close proximity of the shielding films, highdielectric constant material between the shielding films, groundconductors that make direct or indirect electrical contact with at leastone of the shielding films, extended distance between adjacent conductorsets, physical breaks between adjacent conductor sets, intermittentcontact of the shielding films to each other directly eitherlongitudinally, transversely, or both, and conductive adhesive, to namea few. In one aspect, a pinched portion of the shielding films isdefined as a portion of the shielding films that is not covering aconductor set.

FIG. 15 a shows, in cross section, a shielded electrical cable 2202 thatincludes two conductor sets 2204 a, 2204 b spaced apart across a widthof the cable 2202 and extending longitudinally along a length of thecable 2202. Each conductor set 2204 a, 2204 b includes two insulatedconductors 2206 a, 2206 b. Two shielding films 2208 are disposed onopposite sides of the cable 2202. In transverse cross section, coverportions 2207 of the shielding films 2208 substantially surroundconductor sets 2204 a, 2204 b in cover regions 2214 of the cable 2202.For example, the cover portions 2207 of the shielding films 2208 incombination substantially surround each conductor set 2204 a, 2204 b byencompassing at least 70% of a periphery of each conductor set 2204 a,2204 b. In pinched regions 2218 of the cable 2202, on both sides of theconductor sets 2204 a, 2204 b, the shielding films 2208 include pinchedportions 2209. In shielded electrical cable 2202, the pinched portions2209 of shielding films 2208 and insulated conductors 2206 are arrangedgenerally in a single plane when the cable 2202 is in a planar and/orunfolded arrangement. Pinched portions 2209 positioned in betweenconductor sets 2204 a, 2204 b are configured to electrically isolateconductor sets 2204 a, 2204 b from each other.

When arranged in a generally planar, unfolded arrangement, asillustrated in FIG. 15 a, the high frequency electrical isolation of thefirst insulated conductor 2206 a in the conductor set 2204 relative tothe second insulated conductor 2206 b in the conductor set 2204 issubstantially less than the high frequency electrical isolation of thefirst conductor set 2204 a relative to the second conductor set 2204 b.For example, the high frequency isolation of the first insulatedconductor relative to the second conductor is a first far end crosstalkC1 at a specified frequency of 3-15 GHz and a length of 1 meter, and thehigh frequency isolation of the first conductor set relative to theadjacent conductor set is a second far end crosstalk C2 at the specifiedfrequency, and wherein C2 is at least 10 dB lower than C1.

As illustrated in the cross section of FIG. 15 a, the cable 2202 can becharacterized by a maximum separation, D, between the cover portions2207 of the shielding films 2208, a minimum separation, d₂, between thecover portions 2207 of the shielding films 2208, and a minimumseparation, d₁, between the pinched portions 2209 of the shielding films2208. In some embodiments, d₁/D is less than 0.25 or less than 0.1. Insome embodiments, d₂/D is greater than 0.33.

An optional adhesive layer 2210 may be included as shown between thepinched portions 2209 of the shielding films 2208. Adhesive layer 2210may be continuous or discontinuous. In some embodiments, the adhesivelayer extends fully or partially in the cover region 2214 of the cable2202, e.g., between the cover portion 2207 of the shielding films 2208and the insulated conductors 2206 a, 2206 b. The adhesive layer 2210 maybe disposed on the cover portion 2207 of the shielding film 2208 and mayextend fully or partially from the pinched portion 2209 of the shieldingfilm 2208 on one side of a conductor set 2204 a, 2204 b to the pinchedportion 2209 of the shielding film 2208 on the other side of theconductor set 2204 a, 2204 b.

The shielding films 2208 can be characterized by a radius of curvature,R, across a width of the cable 2202 and/or by a radius of curvature, r₁,of the transition portion 2212 of the shielding film and/or by a radiusof curvature, r₂, of the concentric portion 2211 of the shielding film.

In the transition region 2236, the transition portion 2212 of theshielding film 2208 can be arranged to provide a gradual transitionbetween the concentric portion 2211 of the shielding film 2208 and thepinched portion 2209 of the shielding film 2208. The transition portion2212 of the shielding film 2208 extends from a first transition point2221, which is the inflection point of the shielding film 2208 and marksthe end of the concentric portion 2211, to a second transition point2222 where the separation between the shielding films exceeds theminimum separation, d₁, of the pinched portions 2209 by a predeterminedfactor.

In some embodiments, the cable 2202 includes at least one shielding filmthat has a radius of curvature, R, across the width of the cable that isat least about 50 micrometers and/or the minimum radius of curvature,r₁, of the transition portion 2212 of the shielding film 2202 is atleast about 50 micrometers. In some embodiments, the ratio of theminimum radius of curvature of the concentric portion to the minimumradius of curvature of the transition portion, r₂/r₁ is in a range of 2to 15.

FIG. 15 b is a cross sectional view of a shielded electrical cable 2302that includes two conductor sets 2204 spaced apart from each otheracross a width of the cable 2302 and extending longitudinally along alength of the cable 2302. Each conductor set 2304 includes one insulatedconductor 2306, and two shielding films 2308 disposed on opposite sidesof the cable 2302. In transverse cross section, the cover′portions 2307of the shielding films 2308 in combination substantially surround theinsulated conductor 2306 of conductor sets 2304 in a cover region 2314of the cable 2302. In pinched regions 2318 of the cable 2302, on bothsides of the conductor sets 2304, the shielding films 2308 includepinched portions 2309. In shielded electrical cable 2302, pinchedportions 2309 of shielding films 2308 and insulated conductors 2306 canbe arranged generally in a single plane when, the cable 2302 is in aplanar and/or unfolded arrangement. The cover portions 2307 of theshielding films 2308 and/or the pinched portions 2309 of the cable 2302are configured to electrically isolate the conductor sets 2304 from eachother.

As illustrated in the cross section of FIG. 15 b, the cable 2302 can becharacterized by a maximum separation, D, between the cover portions2307 of the shielding films 2308 and a minimum separation, d₁, betweenthe pinched portions 2309 of the shielding films 2308. In someembodiments, d₁/D is less than 0.25, or less than 0.1.

An optional adhesive layer 2310 may be included between the pinchedportions 2309 of the shielding films 2308. Adhesive layer 2310 may becontinuous or discontinuous. In some embodiments, the adhesive layer2310 extends fully or partially in the cover region 2314 of the cable,e.g., between the cover portion 2307 of the shielding films 2308 and theinsulated conductors 2306. The adhesive layer 2310 may be disposed onthe cover portions 2307 of the shielding films 2308 and may extend fullyor partially from the pinched portions 2309 of the shielding films 2308on one side of a conductor set 2304 to the pinched portions 2309 of theshielding films 2308 on the other side of the conductor set 2304.

The shielding films 2308 can be characterized by a radius of curvature,R, across a width of the cable 2302 and/or by a minimum radius ofcurvature, r₁, in the transition portion 2312 of the shielding film 2308and/or by a minimum radius of curvature, r₂, of the concentric portion2311 of the shielding film 2308. In the transition regions 2236 of thecable 2302, transition portions 2312 of the shielding films 2302 can beconfigured to provide a gradual transition between the concentricportions 2311 of the shielding films 2308 and the pinched portions 2309of the shielding films 2308. The transition portion 2312 of theshielding film 2308 extends from a first transition point 2321, which isthe inflection point of the shielding film 2308 and marks the end of theconcentric portion 2311, to a second transition point 2322 where theseparation between the shielding films equals the minimum separation,d₁, of the pinched portions 2309 or exceeds d₁ by a predeterminedfactor, e.g., a factor of about 1.2 or about 1.5.

In some embodiments, the radius of curvature, R, of the shielding filmacross the width of the cable is at least about 50 micrometers and/orthe minimum radius of curvature in the transition portion of theshielding film is at least 50 micrometers.

FIG. 15 c shows, in cross section, a shielded electrical cable 2402 thatincludes two conductor sets 2404 a, 2404 b spaced apart from each otheracross a width of the cable 2402 and extending longitudinally along alength of the cable 2402. Each conductor set 2404 a, 2404 b includes twoinsulated conductors 2206 a, 2206 b. Two shielding films 2408 a, 2408 bare disposed on opposite sides of the cable 2402. In transverse crosssection, cover portions 2407 of the shielding films 2408 a, 2408 b, incombination, substantially surround conductor sets 2404 a, 2404 b in acover region 2414 of the cable 2402. In pinched regions 2418 of thecable 2402 on both sides of the conductor sets 2404 a, 2404 b, the upperand lower shielding films 2408 a, 2408 b include pinched portions 2409.

In shielded electrical cable 2402, pinched portions 2409 of shieldingfilms 2408 and insulated conductors 2406 a, 2406 b are arrangedgenerally in different planes when the cable 2402 is in a planar and/orunfolded arrangement. One of the shielding films 2408 b is substantiallyflat. The portion of the substantially flat shielding film 2408 b in thepinched region 2418 of the cable 2402 is referred to herein as a pinchedportion 2409, even though there is little or no out of plane deviationof the shielding film 2408 b in the pinched region 2418. When the cable2402 is in a planar or unfolded configuration, the concentric 2411,transition 2412, and pinched 2407 portions of shielding film 2408 b aresubstantially coplanar.

The cover portions 2407 and/or the pinched portions 2409 of the cable2402 between conductor sets 2404 a, 2404 b are configured toelectrically isolate the conductor sets 2404 a, 2404 b from each other.When arranged in a generally planar, unfolded arrangement, asillustrated in FIG. 15 c, the high frequency electrical isolation of thefirst insulated conductor 2406 a in the first conductor set 2404 arelative to the second insulated conductor 2406 b in the first conductorset 2404 a is substantially less than the high frequency electricalisolation of either conductor 2406 a, 2406 b of the first conductor set2404 a relative to either conductor 2406 a, 2406 b of the secondconductor set 2404 b, as previously discussed.

As illustrated in the cross section of FIG. 15 c, the cable 2402 can becharacterized by a maximum separation, D, between the cover portions2407 of the shielding films 2408 a; 2408 b, a minimum separation, d₂,between the cover portions 2407 of the shielding films 2408 a, 2408 b,and a minimum separation, d₁, between the pinched portions 2409 of theshielding films 2408 a, 2408 b. In some embodiments, d₁/D is less than0.25, or less than 0.1. In some embodiments, d₂/D is greater than 0.33.

An optional adhesive layer 2410 may be disposed between the pinchedportions 2409 of the shielding films 2408 a, 2408 b. Adhesive layer 2410may be continuous or discontinuous. In some embodiments, the adhesivelayer 2410 extends fully or partially in the cover region 2414 of thecable 2402, e.g., between the cover portions 2407 of one or more of theshielding films 2408 a, 2408 b and the insulated conductors 2406 a, 2406b. The adhesive layer 2410 may be disposed on the cover portion 2407 ofone or more shielding films 2408 a, 2408 b and may extend fully orpartially from the pinched portion 2409 of the shielding films 2408 a,2408 b on one side of a conductor set 2404 a, 2404 b to the pinchedportions 2409 of the shielding films 2408 a, 2408 b on the other side ofthe conductor set 2404 a, 2404 b.

The transition portions 2412 of the curved shielding film 2408 a providea gradual transition between the concentric portions 2411 of theshielding film 2408 a and the pinched portions 2409 of the shieldingfilm 2408 a. The transition portions 2412 of the shielding film 2408 aextends from a first transition point 2421 a, which is the inflectionpoint of the shielding film 2408 a to a second transition point 2422 awhere the separation between the shielding films is equal to the minimumseparation, d₁, of the pinched portions 2409, or exceeds d₁ by apredetermined factor. The transition portion of the substantially flatshielding film 2808 b extends from a first transition point 2421 b to asecond transition point 2422 b where the separation between theshielding films is equal to the minimum separation, d₁, of the pinchedportions 2409, or exceeds d₁ by a predetermined factor. The firsttransition point 2421 b is defined by a line perpendicular to thesubstantially flat shielding film 2408 b which intersects the firsttransition point 2421 a of the shielding film 2408 a.

Curved shielding film 2408 a can be characterized by a radius ofcurvature, R, across a width of the cable 2402 and/or by a minimumradius of curvature, r₁, of the transition portions 2412 of theshielding film 2408 a and/or by a minimum radius of curvature, r₂, ofthe concentric portions 2411 of the shielding film. In some embodiments,the cable 2402 includes at least one shielding film 2408 that has aradius of curvature across the width of the cable that is at least about50 micrometers and/or a minimum radius of curvature, r₁, of thetransition portion of the shielding film that is at least about 50micrometers. In some embodiments, the ratio r₂/r₁ of the minimum radiusof curvature, r₂, of the concentric portion of the shielding film to theminimum radius of curvature, r₁, of the transition portion of theshielding film is in a range of 2 to 15.

In FIG. 16 a, shielded electrical cable 2502 includes a pinched region2518 wherein shielding films 2508 are spaced apart by a distance.Spacing apart shielding films 2508, i.e., not having shielding films2508 make direct electrical contact continuously along their seam,increases the strength of pinched region 2518. Shielded electricalcables having relatively thin and fragile shielding films may fractureor crack during manufacturing if forced to make direct electricalcontact continuously along their seam. Spacing apart shielding films2508 may permit crosstalk between adjacent conductor sets if effectivemeans are not used to reduce the crosstalk potential. Reducing crosstalkinvolves containing the electrical and magnetic fields of one conductorset so that they to not impinge on an adjacent conductor set. In theembodiment illustrated in FIG. 16 a, an effective shield againstcrosstalk is achieved by providing a low DC resistance between shieldingfilms 2508. A low DC resistance can be achieved by orienting theshielding films 2508 in close proximity. For example, pinched portions2509 of shielding films 2508 may be spaced apart by less than about 0.13mm in at least one location of pinched region 2518. The resulting DCresistance between shielding films 2508 may be less than about 15 ohms,and the resulting crosstalk between adjacent conductor sets may be lessthan about −25 dB. In some cases, the pinched region 2518 of the cable2502 has a minimum thickness of less than about 0.13 mm.

The shielding films 2508 can be spaced apart by a separation medium. Theseparation medium may include conformable adhesive layer 2510. Forexample, the separation medium may have a dielectric constant of atleast 1.5. A high dielectric constant decreases the impedance betweenshielding films 2508, thereby increasing the electrical isolation anddecreasing the crosstalk between adjacent conductor sets. Shieldingfilms 2508 may make direct electrical contact with each other in atleast one location of pinched region 2518′. Shielding films 2508 may beforced together in selected locations so that the thickness ofconformable adhesive layer 2510 is reduced in the selected locations.Forcing the shielding film together in selected locations may beaccomplished, for example, with a patterned tool making intermittentpinch contact between shielding films 2508 in these locations. Theselocations may be patterned longitudinally or transversely. In somecases, the separation medium may be electrically conductive to enabledirect electrical contact between shielding films 2508.

In FIG. 16 b, shielded electrical cable 2602 includes a pinched region2618 including a ground conductor 2612 disposed between shielding films2608 and extending along a length of the cable 2602. The groundconductor 2612 may make indirect electrical contact with both shieldingfilms 2608, e.g., a low but non-zero DC resistance between the shieldingfilms 2608. In some cases, the ground conductor 2612 may make direct orindirect electrical contact with at least one of the shielding films2608 in at least one location of pinched region 2618. The shieldedelectrical cable 2602 may include a conformable adhesive layer 2610disposed between shielding films 2608 and configured to providecontrolled separation of at least one of shielding films 2608 and groundconductor 2612. The conformable adhesive layer 2610 may have anon-uniform thickness that allows ground conductor 2612 to make director indirect electrical contact with at least one of shielding films 2608in selective locations. In some cases, the ground conductor 2612 mayinclude surface asperities or a deformable wire, such as, e.g., astranded wire, to provide the controlled electrical contact betweenground conductor 2612 and at least one of shielding films 2608.

In FIG. 16 c, shielded electrical cable 2702 includes a pinched region2718. A ground conductor 2712 disposed between shielding films 2708 andmakes direct electrical contact with both shielding films 2708.

In FIG. 16 d, shielded electrical cable 2802 includes a pinched region2818 wherein shielding films 2808 make direct electrical contact witheach other by any suitable means, such as, e.g., conductive element2844. Conductive element 2844 may include a conductive plated via orchannel, a conductive filled via or channel, or a conductive adhesive,to name a few.

In FIG. 16 e, shielded electrical cable 2902 includes a pinched region2918 that has an opening 2936 in at least one location of the pinchedregion 2918. In other words, pinched region 2918 is discontinuous.Opening 2936 may include a hole, a perforation, a slit, and any othersuitable element. Opening 2936 provides at least some level of physicalseparation, which contributes to the electrical isolation performance ofpinched region 2918 and increases at least the lateral flexibility ofshielded electrical cable 2902. This separation may be discontinuousalong the length of pinched region 2918, and may be discontinuous acrossthe width of pinched region 2918.

In FIG. 16 f, shielded electrical cable 3002 includes a pinched region3018 where at least one of shielding films 3008 includes a break 3038 inat least one location of pinched region 3018. In other words, at leastone of shielding films 3008 is discontinuous. Break 3038 may include ahole, a perforation, a slit, and any other suitable element. Break 3038provides at least some level of physical separation, which contributesto the electrical isolation performance of pinched region 3018 andincreases at least the lateral flexibility of shielded electrical cable3002. This separation may be discontinuous or continuous along thelength of pinched region, and may be discontinuous across the width ofthe pinched portion 3018.

In FIG. 16 g, shielded electrical cable 3102 includes a pinched region3118 that is piecewise planar in a folded configuration. All otherthings being equal, a piecewise planar pinched region has a greateractual surface area than a planar pinched region having the sameprojected width. If the surface area of a pinched region is much greaterthan the spacing between the shielding films 3108, the DC resistance isdecreased which improves the electrical isolation performance of thepinched region 3118. In one embodiment, a DC resistance of less than 5to 10 Ohms results in good electrical isolation. In one embodiment,parallel portion 3118 of shielded electrical cable 3102 has an actualwidth to minimum spacing ratio of at least 5. In one embodiment, pinchedregion 3118 is pre-bent and thereby increases at least the lateralflexibility of shielded electrical cable 3102. Pinched region 3118 maybe piecewise planar in any other suitable configuration.

FIGS. 17 a-17 b, illustrate details pertaining to a pinched regionduring the manufacture of an exemplary shielded electrical cable.Shielded electrical cable 3202 includes two shielding films 3208 andincludes a pinched region 3218 (wherein FIG. 17 b) is made whereinshielding films 3208 may be substantially parallel. Shielding films 3208include a non-conductive polymeric layer 3208 b, a conductive layer 3208a disposed on non-conductive polymeric layer 3208 b, and a stop layer3208 d disposed on the conductive layer 3208 a. A conformable adhesivelayer 3210 is disposed on stop layer 3208 d. Pinched region 3218includes a longitudinal ground conductor 3212 disposed between shieldingfilms 3208.

After the shielding films are forced together around the groundconductor, the ground conductor 3212 makes indirect electrical contactwith conductive layers 3208 a of the shielding films 3208. This indirectelectrical contact is enabled by a controlled separation of conductivelayer 3208 a and ground conductor 3212 provided by stop layer 3208 d. Insome cases, the stop layer 3208 d may be or include a non-conductivepolymeric layer. As shown in the figures, an external pressure (see FIG.17 a) is used to press conductive layers 3208 a together and forceconformable adhesive layers 3210 to conform around the ground conductorthe (FIG. 17 b). Because stop layer 3208 d does not conform at leastunder the same processing conditions, it prevents direct electricalcontact between the ground conductor 3212 and conductive layer 3208 a ofshielding films 3208, but achieves indirect electrical contact. Thethickness and dielectric properties of stop layer 3208 d may be selectedto achieve a low target DC resistance, i.e., electrical contact of anindirect type. In some embodiments, the characteristic DC resistancebetween the ground conductor and the shielding film may be less than 10ohms, or less than 5 ohms, for example, but greater than 0 ohms, toachieve the desired indirect electrical contact. In some cases, it isdesirable to make direct electrical contact between a given groundconductor and one or two shielding films, whereupon the DC resistancebetween such ground conductor and such shielding film(s) may besubstantially 0 ohms.

FIG. 18 shows a folded shielded cable 3302. Shielded cable 3302 includestwo shielding films 3308 disposed around spaced apart conductor sets3304. Shielding films 3308 are disposed on opposite sides of the cable3302 and include pinched regions 3318 on each side of the conductor sets3304. The pinched regions 3318 are configured to be laterally bent at anangle α of at least 30°. This lateral flexibility of pinched regions3318 enables shielded electrical cable 3302 to be folded in any suitableconfiguration, such as, e.g., a configuration that can be used in around cable (see, e.g., FIG. 10 g). In one embodiment, the shieldingfilms 3308 having relatively thin individual layers increases thelateral flexibility of pinched regions 3318. To maintain the integrityof these individual layers in particular under bending conditions, it ispreferred that the bonds between them remain intact. For example, forpinched regions 3318 may have a minimum thickness of less than about0.13 mm, and a bond strength between individual layers of at least 17.86g/mm (1 lbs/inch) after thermal exposures during processing or use.

In one aspect, it is beneficial to the electrical performance of ashielded electrical cable for the pinched regions to have approximatelythe same size and shape on both sides of a conductor set. Anydimensional changes or imbalances may produce imbalances in capacitanceand inductance along the length of the parallel portion. This in turnmay cause impedance differences along the length of the pinched regionand impedance imbalances between adjacent conductor sets. At least forthese reasons, control of the spacing between the shielding films may bedesired. In some cases, the pinched portions of the shielding films inthe pinched regions of the cable on both sides of a conductor set arespaced apart within about 0.05 mm of each other.

In FIG. 19, shielded electrical cable 3402 includes two conductor sets3404, each including two insulated conductors 3406, and two generallyshielding films 3408 disposed on opposite sides of the electrical cable3402 around conductor sets 3404. Shielding films 3408 include pinchedportions 3418. Pinched portions 3418 are positioned at or near an edgeof shielded electrical cable 3402 are configured to electrically isolateconductor sets 3404 from the external environment. In shieldedelectrical cable 3402, pinched portions 3418 of shielding films 3408 andinsulated conductors 3406 are arranged generally in a single plane.

In FIG. 20 a, shielded electrical cable 3502 includes a pinched region3518 wherein pinched portions 3509 of shielding films 3508 are spacedapart. Pinched region 3518 is similar to pinched region 2518 describedabove and illustrated in FIG. 16 a. Whereas pinched region 2518 ispositioned in between conductor sets, pinched region 3518 is positionedat or near an edge of shielded electrical cable 3502.

In FIG. 20 b, shielded electrical cable 3602 includes a pinched region3618 that includes a longitudinal ground conductor 3612 disposed betweenshielding films 3608. Pinched region 3618 is similar to pinched region2618 described above and illustrated in FIG. 16 b. Whereas pinchedregion 2618 is positioned in between conductor sets, pinched region 3618is positioned at or near an edge of shielded electrical cable 3602.

In FIG. 20 c, shielded electrical cable 3702 includes a pinched region3718 including a longitudinal ground conductor 3712 disposed betweenshielding films 3708. Pinched region 3718 is similar to pinched region2718 described above and illustrated in FIG. 16 c. Whereas pinchedregion 2718 is positioned in between conductor sets, pinched region 3718is positioned at or near an edge of shielded electrical cable 3702.

In FIG. 20 d, shielded electrical cable 3802 includes a pinched region3818 wherein the pinched portions 3809 of shielding films 3808 makedirect electrical contact with each other by any suitable means, suchas, e.g., conductive element 3844. Conductive element 3844 may include aconductive plated via or channel, a conductive filled via or channel, ora conductive adhesive, to name a few. Pinched region 3818 is similar topinched region 2818 described above and illustrated in FIG. 16 d.Whereas pinched region 2818 is positioned in between conductor sets,pinched region 3818 is positioned at or near an edge of shieldedelectrical cable 3802.

In FIG. 20 e, shielded electrical cable 3902 includes a pinched region3918 that is piecewise planar in a folded configuration. Pinched region3918 is similar to pinched region 3118 described above and illustratedin FIG. 16 g. Whereas pinched region 3118 is positioned in betweenconductor sets, pinched region 3918 is positioned at or near an edge ofshielded electrical cable 3902.

In FIG. 20 f, shielded electrical cable 4002 includes a pinched region4018 that is piecewise planar in a curved configuration and positionedat or near an edge of shielded electrical cable 4002.

A shielded electrical cable according to an aspect of the presentinvention may include at least one longitudinal ground conductor, anelectrical article extending in substantially the same direction as theground conductor, and two shielding films disposed on opposite sides ofthe shielded electrical cable. In transverse cross section, theshielding films substantially surround the ground conductor and theelectrical article. In this configuration, the shielding films andground conductor are configured to electrically isolate the electricalarticle. The ground conductor may extend beyond at least one of the endsof the shielding films, e.g., for termination of the shielding films toany suitable individual contact element of any suitable terminationpoint, such as, e.g., a contact element on a printed circuit board or anelectrical contact of an electrical connector. Beneficially, only alimited number of ground conductors is needed for a cable construction,and can, along with the shielding films, complete an electromagneticenclosure of the electrical article. The electrical article may includeat least one conductor that extends along a length of the cable, atleast one conductor set that extends along a length of the cableincluding one or more insulated conductors, a flexible printed circuit,or any other suitable electrical article of which electrical isolationis desired. FIGS. 21 a-21 b illustrate two exemplary embodiments of suchshielded electrical cable configuration.

In FIG. 21 a, shielded electrical cable 4102 includes two spaced apartground conductors 4112 that extend along a length of the cable 4102, anelectrical article 4140 positioned between and extending insubstantially the same direction as ground conductors 4112, and twoshielding films 4108 disposed on opposite sides of the cable. Intransverse cross section, the shielding films 4108, in combination,substantially surround ground conductors 4112 and electrical article4140.

Electrical article 4140 includes three conductor sets 4104 that arespaced apart across a width of the cable 4102. Each conductor set 4104includes two substantially insulated conductors 4106 that extend along alength of the cable. Ground conductors 4112 may make indirect electricalcontact with both shielding films 4108 resulting in a low but non-zeroimpedance between the ground conductors 4112 and the shielding films4108. In some cases, ground conductors 4112 may make direct or indirectelectrical contact with at least one of the shielding films 4108 in atleast one location of shielding films 4108. In some cases, an adhesivelayer 4110 is disposed between the shielding films 4108 and bonds theshielding films 4108 to each other on both sides of ground conductors4112 and electrical article 4140. Adhesive layer 4110 can be configuredto provide controlled separation of at least one of shielding films 4108and ground conductors 4112. In one aspect, this means that adhesivelayer 4110 has a non-uniform thickness that allows ground conductors4112 to make direct or indirect electrical contact with at least one ofshielding films 4108 in selective locations. The ground conductors 4112may include surface asperities or a deformable wire, such as, e.g., astranded wire, to provide this controlled electrical contact betweenground conductors 4112 and at least one of shielding films 4108. Theshielding films 4108 can be spaced apart by a minimum spacing in atleast one location of shielding films 4108, where ground conductors 4112have a thickness that is greater than the minimum spacing. For example,the shielding films 4108 may have a thickness of less than about 0.025mm.

In FIG. 22, shielded electrical cable 4202 includes two spaced apartground conductors 4212 that extend along a length of the cable 4202, anelectrical article 4240 positioned between and extending insubstantially the same direction as ground conductors 4212, and twoshielding films 4208 disposed on opposite sides of the cable 4202. Intransverse cross section, the shielding films, in combination,substantially surround ground conductors 4212 and electrical article4240. Shielded electrical cable 4202 is similar in some respects toshielded electrical cable 4102 described above and illustrated in FIG.21 a. Whereas in shielded electrical cable 4102, electrical article 4140includes three conductor sets 4104 each including two substantiallyparallel longitudinal insulated conductors 4106, in shielded electricalcable 4202, electrical article 4240 includes a flexible printed circuitincluding three conductor sets 4242.

In exemplary embodiments described above, the shielded electrical cableincludes two shielding films disposed on opposite sides of the cablesuch that, in transverse cross section, cover portions of the shieldingfilms in combination substantially surround a given conductor set, andsurround each of the spaced apart conductor sets individually. In someembodiments, however, the shielded electrical cable may contain only oneshielding film, which is disposed on only one side of the cable.Advantages of including only a single shielding film in the shieldedcable, compared to shielded cables having two shielding films, include adecrease in material cost and an increase in mechanical flexibility,manufacturability, and ease of stripping and termination. A singleshielding film may provide an acceptable level of electromagneticinterference (EMI) isolation for a given application, and may reduce theproximity effect thereby decreasing signal attenuation. FIG. 13illustrates one example of such a shielded electrical cable thatincludes only one shielding film.

Shielded electrical cable 4302, illustrated in FIG. 23, includes twospaced apart conductor sets 4304 and a single shielding film 4308. Eachconductor set 4304 includes a single insulated conductor 4306 thatextends along a length of the cable 4302. Insulated conductors 4306 arearranged generally in a single plane and effectively in a coaxial cableconfiguration that can be used in a single ended circuit arrangement.Cable 4302 includes pinched regions 4318. In the pinched regions 4318,the shielding film 4308 includes pinched portions 4309 extending fromboth sides of each conductor set 4304. Pinched regions 4318cooperatively define a generally planar shielding film. The shieldingfilm 4308 includes two cover portions 4307 each partially covering aconductor set 4304. Each cover portion 4307 includes a concentricportion 4311 substantially concentric with corresponding conductor 4306.Shielding film 4308 includes a conductive layer 4308 a and anon-conductive polymeric layer 4308 b. The conductive layer 4308 a facesthe insulated conductors 4306. The cable 4302 may optionally include annon-conductive carrier film 4346. Carrier film 4346 includes pinchedportions 4346″ that extend from both sides of each conductor set 4304and opposite pinched portions 4309 of the shielding film 4308. Thecarrier film 4346 includes two cover portions 4346′″ each partiallycovering a conductor set 4304 opposite cover portion 4307 of shieldingfilm 4308. Each cover portion 4346′″ includes a concentric portion 4346′substantially concentric with corresponding conductor 4306. Carrier film4346 may include any suitable polymeric material, including but notlimited to polyester, polyimide, polyamide-imide,polytetrafluoroethylene, polypropylene, polyethylene, polyphenylenesulfide, polyethylene naphthalate, polycarbonate, silicone rubber,ethylene propylene diene rubber, polyurethane, acrylates, silicones,natural rubber, epoxies, and synthetic rubber adhesive. Carrier film4346 may include one or more additives and/or fillers to provideproperties suitable for the intended application. Carrier film 4346 maybe used to complete physical coverage of conductor sets 4304 and add tothe mechanical stability of shielded electrical cable 4302.

Referring to FIG. 24, shielded electrical cable 4402 is similar in somerespects to shielded electrical cable 4302 described above andillustrated in FIG. 23. Whereas shielded electrical cable 4302 includesconductor sets 4304 each including a single insulated conductor 4306,shielded electrical cable 4402 includes conductor sets 4404 that havetwo insulated conductors 4406. The insulated conductors 4406 arearranged generally in a single plane and effectively in a twinaxialcable configuration which can be used in a single ended or differentialpair circuit arrangement.

Referring to FIG. 25, shielded electrical cable 4502 is similar in somerespects to shielded electrical cable 4402 described above andillustrated in FIG. 24. Whereas shielded electrical cable 4402 hasindividually insulated conductors 4406, shielded electrical cable 4502has jointly insulated conductors 4506.

In one aspect, as can be seen in FIGS. 23-25, the shielding film isre-entrant between adjacent conductor sets. In other words, theshielding film includes a pinched portion that is disposed betweenadjacent conductor sets. This pinched portion is configured toelectrically isolate the adjacent conductor sets from each other. Thepinched portion may eliminate the need for a ground conductor to bepositioned between adjacent conductor sets, which simplifies the cableconstruction and increases the cable flexibility, among other benefits.The pinched portion may be positioned at a depth d (FIG. 23) that isgreater than about one third of the diameter of the insulatedconductors. In some cases, the pinched portion may be positioned at adepth d that is greater than about one half of the diameter of theinsulated conductors. Depending on the spacing between adjacentconductor sets, the transmission distance, and the signaling scheme(differential versus single-ended), this re-entrant configuration of theshielding film more than adequately electrically isolates the conductorsets from each other.

The conductor sets and shielding film may be cooperatively configured inan impedance controlling relationship. In one aspect, this means thatthe partial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry along the length ofthe shielded electrical cable such as to provide an acceptable impedancevariation as suitable for the intended application. In one embodiment,this impedance variation is less than 5 Ohms and preferably less than 3Ohms along a representative cable length, such as, e.g., 1 m. In anotheraspect, if the insulated conductors are arranged effectively in atwinaxial and/or differential pair cable arrangement, this means thatthe partial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry between theinsulated conductors of a pair such as to provide an acceptableimpedance variation as suitable for the intended application. In somecases, the impedance variation is less than 2 Ohms and preferably lessthan 0.5 Ohms along a representative cable length, such as, e.g., 1 m.

FIGS. 26 a-26 d illustrate various examples of partial coverage of theconductor set by the shielding film. The amount of coverage by theshielding film varies between the embodiments. In the embodimentillustrated in FIG. 26 a, the conductor set has the most coverage. Inthe embodiment illustrated in FIG. 26 d, the conductor set has the leastcoverage. In the embodiments illustrated in FIGS. 26 a and 26 b, morethan half of the periphery of the conductor set is covered by theshielding film. In the embodiments illustrated in FIGS. 26 c and 26 d,less than half of the periphery of the conductor set is covered by theshielding film. A greater amount of coverage provides betterelectromagnetic interference (EMI) isolation and reduced signalattenuation (resulting from a reduction in the proximity effect).

Referring to FIG. 26 a, shielded electrical cable 4602 includes aconductor set 4604 and a shielding film 4608. Conductor set 4604includes two insulated conductors 4606 which extend along a length ofthe cable 4602. Shielding film 4608 includes pinched portions 4609extending from both sides of conductor set 4604. Pinched portions 4609cooperatively define a generally planar shielding film. Shielding film4608 further includes a cover portion 4607 partially covering conductorset 4604. Cover portion 4607 includes concentric portions 4611substantially concentric with a corresponding end conductor 4306 of theconductor set 4604. Shielded electrical cable 4602 may also have anoptional non-conductive carrier film 4646. Carrier film 4646 includespinched portions 4646″ extending from both sides of conductor set 4604and disposed opposite pinched portions 4609 of shielding film 4608.Carrier film 4646 further includes a cover portion 4646′ partiallycovering conductor set 4604 opposite cover portion 4607 of shieldingfilm 4608. Cover portion 4607 of shielding film 4608 covers the top sideand the entire left and right sides of conductor set 4604. Cover portion4646″ of carrier film 4646 covers the bottom side of conductor set 4604,completing the substantial enclosure of conductor set 4604. In thisembodiment, pinched portions 4646″ and cover portion 4646″ of carrierfilm 4646 are substantially coplanar.

Referring to FIG. 26 b, shielded electrical cable 4702 is similar insome respects to shielded electrical cable 4602 described above andillustrated in FIG. 26 a. However, in shielded electrical cable 4702,the cover portion 4707 of shielding film 4708 covers the top side andmore than half of the left and right sides of conductor set 4704. Thecover portion 4746″ of carrier film 4746 covers the bottom side and theremainder (less than half) of the left and right sides of conductor set4704, completing the substantial enclosure of conductor set 4704. Coverportion 4746′″ of carrier film 4746 includes concentric portions 4746′substantially concentric with corresponding conductor 4706.

Referring to FIG. 26 c, shielded electrical cable 4802 is similar insome respects to shielded electrical cable 4602 described above andillustrated in FIG. 26 a. In shielded electrical cable 4802, the coverportion 4807 of shielding film 4808 covers the bottom side and less thanhalf of the left and right sides of conductor set 4804. Cover portion4846′ of carrier film 4846 covers the top side and the remainder (morethan half) of the left and right sides of conductor set 4804, completingthe enclosure of conductor set 4804.

Referring to FIG. 26 d, shielded electrical cable 4902 is similar toshielded electrical cable 4602 described above and illustrated in FIG.26 a. However, in shielded electrical cable 4902, cover portion 4907 ofshielding film 4908 covers the bottom side of conductor set 4904. Coverportion 4946′ of carrier film 4946 covers the top side and the entireleft and right sides of conductor set 4904, completing the substantialenclosure of conductor set 4904. In some cases, pinched portions 4909and cover portion 4907 of shielding film 4908 are substantiallycoplanar.

Similar to embodiments of the shielded electrical cable including twoshielding films disposed on opposite sides of the cable around aconductor set and/or around a plurality of spaced apart conductor sets,embodiments of the shielded electrical cable including a singleshielding film may include at least one longitudinal ground conductor.In one aspect, this ground conductor facilitates electrical contact ofthe shielding film to any suitable individual contact element, of anysuitable termination point, such as, e.g., a contact element on aprinted circuit board or an electrical contact of an electricalconnector. The ground conductor may extend beyond at least one of theends of the shielding film to facilitate this electrical contact. Theground conductor may make direct or indirect electrical contact with theshielding film in at least one location along its length, and may beplaced in suitable locations of the shielded electrical cable.

FIG. 27 illustrates a shielded electrical cable 5002 having only oneshielding film 5008. Insulated conductors 5006 are arranged in twoconductor sets 5004, each having only one pair of insulated conductors,although conductor sets having other numbers of insulated conductors asdiscussed herein are also contemplated. Shielded electrical cable 5002is shown to include ground conductors 5012 in various exemplarylocations but any or all of the ground conductors 5012 may be omitted ifdesired, or additional ground conductors can be included. Groundconductors 5012 extend in substantially the same direction as insulatedconductors 5006 of conductor sets 5004 and are positioned betweenshielding film 5008 and carrier film 5046. One ground conductor 5012 isincluded in a pinched portion 5009 of shielding film 5008 and threeground conductors 5012 are included in a conductor set 5004. One ofthese three ground conductors 5012 is positioned between insulatedconductors 5006 and shielding film 5008 and two of these three groundconductors 5012 and insulated conductors 5006 are arranged generally ina single plane.

FIGS. 28 a-28 d are cross sectional views that illustrate variousexemplary embodiments of a shielded electrical cable according toaspects of the present invention. FIGS. 28 a-28 d illustrate variousexamples of partial coverage of the conductor set by the shielding filmwithout the presence of a carrier film. The amount of coverage by theshielding film varies between the embodiments. In the embodimentillustrated in FIG. 28 a, the conductor set has the most coverage. Inthe embodiment illustrated in FIG. 28 d, the conductor set has the leastcoverage. In the embodiments illustrated in FIGS. 28 a and 28 b, morethan half of the periphery of the conductor set is covered by theshielding film. In the embodiment illustrated in FIG. 28 c, about halfof the periphery of the conductor set is covered by the shielding film.In the embodiment illustrated in FIG. 28 d, less than half of theperiphery of the conductor set is covered by the shielding film. Agreater amount of coverage provides better electromagnetic interference(EMI) isolation and reduced signal attenuation (resulting from areduction in the proximity effect). Although in these embodiments, aconductor set includes two substantially parallel longitudinal insulatedconductors, in other embodiments, a conductor set may include one ormore than two substantially parallel longitudinal insulated conductors.

Referring to FIG. 28 a, a shielded electrical cable 5102 includes aconductor set 5104 and a shielding film 5108. The conductor set 5104includes two insulated conductors 5106 that extend along a length of thecable 5102. Shielding film 5108 includes pinched portions 5109 extendingfrom both sides of conductor set 5104. Pinched portions 5109cooperatively define a generally planar shielding film. Shielding film5108 further includes a cover portion 5107 partially covering conductorset 5104. Cover portion 5107 includes concentric portions 5111substantially concentric with a corresponding end conductor 5106 of theconductor 5104. Cover portion 5107 of shielding film 5108 covers thebottom side and the entire left and right sides of conductor set 5104 inFIG. 28 a.

Referring to FIG. 28 b, shielded electrical cable 5202 is similar insome respects to shielded electrical cable 5102 described above andillustrated in FIG. 28 a. However, in shielded electrical cable 5202,cover portion 5207 of shielding film 5208 covers the bottom side andmore than half of the left and right sides of conductor set 5204.

Referring to FIG. 28 c, shielded electrical cable 5302 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28 a. However, in shielded electrical cable 5302, cover portion 5307 ofshielding film 5308 covers the bottom side and about half of the leftand right sides of conductor set 5304.

Referring to FIG. 28 d, shielded electrical cable 5402 is similar insome respects to shielded electrical cable 5102 described above andillustrated in FIG. 28 a. However, in shielded electrical cable 5402,cover portion 5411 of shielding film 5408 covers the bottom side andless than half of the left and right sides of conductor set 5404.

As an alternative to a carrier film, for example, shielded electricalcables according to aspects of the present invention may include anoptional non-conductive support. This support may be used to completephysical coverage of a conductor set and add to the mechanical stabilityof the shielded electrical cable. FIGS. 29 a-29 d are cross sectionalviews that illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includinga non-conductive support. Although in these embodiments, anon-conductive support is used with a conductor set that includes twoinsulated conductors, in other embodiments, a non-conductive support maybe used with a conductor set that includes one or more than twosubstantially parallel longitudinal insulated conductors, or with aground conductor. The support may include any suitable polymericmaterial, including but not limited to polyester, polyimide,polyamide-imide, polytetrafluoroethylene, polypropylene, polyethylene,polyphenylene sulfide, polyethylene naphthalate, polycarbonate, siliconerubber, ethylene propylene diene rubber, polyurethane, acrylates,silicones, natural rubber, epoxies, and synthetic rubber adhesive. Thesupport may include one or more additives and/or fillers to provideproperties suitable for the intended application.

Referring to FIG. 29 a, shielded electrical cable 5502 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28 a, but further includes a non-conductive support 5548 partiallycovering conductor set 5504 opposite cover portion 5507 of shieldingfilm 5508. The support 5548 can cover the top side of conductor set5504, to enclose insulated conductors 5506. The support 5548 includes agenerally planar top surface 5548 a. Top surface 5548 a and pinchedportions 5509 of the shielding film 5508 are substantially coplanar.

Referring to FIG. 29 b, shielded electrical cable 5602 is similar toshielded electrical cable 5202 described above and illustrated in FIG.28 b, but further includes a non-conductive support 5648 partiallycovering conductor set 5604 opposite cover portion 5607 of shieldingfilm 5608. Support 5648 only partially covers the top side of conductorset 5604, leaving insulated conductors 5606 partially exposed.

Referring to FIG. 29 c, shielded electrical cable 5702 is similar toshielded electrical cable 5302 described above and illustrated in FIG.28 c, but further includes a non-conductive support 5748 partiallycovering conductor set 5704 opposite cover portion 5707 of shieldingfilm 5708. Support 5748 covers essentially the entire top side ofconductor set 5704, essentially fully enclosing insulated conductors5706. At least a portion of support 5748 is substantially concentricwith insulated conductors 5706. A portion of support 5748 is disposedbetween insulated conductors 5706 and shielding film 5708.

Referring to FIG. 29 d, shielded electrical cable 5802 is similar toshielded electrical cable 5402 described above and illustrated in FIG.28 d, but further includes a non-conductive support 5848 partiallycovering conductor set 5804 opposite cover portion 5807 of shieldingfilm 5808. Support 5848 only partially covers the top side of conductorset 5804, leaving insulated conductors 5806 partially exposed. A portionof support 5848 is disposed between insulated conductors 5806 andshielding film 5808.

Additional discussion of shielded cables is provided in “ConnectorArrangements for Shielded Electrical Cables” (Attorney Docket66887US002) filed on even date herewith and incorporated herein byreference.

We now provide, further details regarding shielded ribbon cables thatcan employ high packing density of mutually shielded conductor sets. Thedesign features of the disclosed cables allow them to be manufactured ina format that allows very high density of signal lines in a singleribbon cable. This can enable a high density mating interface and ultrathin connector, and/or can enable crosstalk isolation with standardconnector interfaces. In addition, high density cable can reduce themanufacturing cost per signal pair, reduce the bending stiffness of theassembly of pairs (for example, in general, one ribbon of high densitybends more easily than two stacked ribbons of lower density), and reducethe total thickness since one ribbon is generally thinner than twostacked ribbons.

One potential application for at least some of the disclosed shieldedcables is in high speed (I/O) data transfer between components ordevices of a computer system or other electronic system. A protocolknown as SAS (Serial Attached SCSI), which is maintained by theInternational Committee for Information Technology Standards (INCITS),is a computer bus protocol involving the movement of data to and fromcomputer storage devices such as hard drives and tape drives. SAS usesthe standard SCSI command set and involves a point-to-point serialprotocol. A convention known as mini-SAS has been developed for certaintypes of connectors within the SAS specification.

Conventional twinaxial (twinax) cable assemblies for internalapplications, such as mini-SAS cable assemblies, utilize individualtwinax pairs, each pair having its own accompanying drain wire, and insome cases two drain wires. When terminating such a cable, not only musteach insulated conductor of each twinax pair be managed, but each drainwire (or both drain wires) for each twinax pair must also be managed.These conventional twinax pairs are typically arranged in a loose bundlethat is placed within a loose outer braid that contains the pairs sothat they can be routed together. In contrast, the shielded ribboncables described herein can if desired be used in configurations where,for example, a first four-pair ribbon cable is mated to one majorsurface of the paddle card (see e.g. FIG. 3 d above) and a secondfour-pair ribbon cable, which may be similar or substantially identicalin configuration or layout to the first four-pair ribbon cable, is matedto the other major surface at the same end of the paddle card to make a4x or 4i mini-SAS assembly, having 4 transmit shielded pairs and 4receive shielded pairs. This configuration is advantageous relative tothe construction utilizing the twinax pairs of a conventional cable, inpart because fewer than one drain wire per twinax pair can be used, andthus fewer drain wires need to be managed for termination. However, theconfiguration utilizing the stack of two four-pair ribbon cables retainsthe limitation that two separate ribbons are needed to provide a 4x/4iassembly, with the concomitant requirement to manage two ribbons, andwith the disadvantageous increased stiffness and thickness of tworibbons relative to only one ribbon.

We have found that the disclosed shielded ribbon cables can be madedensely enough, i.e., with a small enough wire-to-wire spacing, a smallenough conductor set-to-conductor set spacing, and with a small enoughnumber of drain wires and drain wire spacing, and with adequate losscharacteristics and crosstalk or shielding characteristics, to allow fora single ribbon cable, or multiple ribbon cables arranged side-by-siderather than in a stacked configuration, to extend along a single planeto mate with a connector. This ribbon cable or cables may contain atleast three twinax pairs total, and if multiple cables are used, atleast one ribbon may contain at least two twinax pairs. In an exemplaryembodiment, a single ribbon cable may be used, and if desired, thesignal pairs may be routed to two planes or major surfaces of aconnector or other termination component, even though the ribbon cableextends along only one plane. The routing can be achieved in a number ofways, e.g., tips or ends of individual conductors can be bent out of theplane of the ribbon cable to contact one or the other major surface ofthe termination component, or the termination component may utilizeconductive through-holes or vias that connect one conductive pathwayportion on one major surface to another conductive pathway portion onthe other major surface, for example. Of particular significance to highdensity cables, the ribbon cable also preferably contains fewer drainwires than conductor sets; in cases where some or all of the conductorsets are twinax pairs, i.e., some or all of the conductor sets eachcontains only one pair of insulated conductors, the number of drainwires is preferably less than the number of twinax pairs. Reducing thenumber of drain wires allows the width of the cable to be reduced sincedrain wires in a given cable are typically spaced apart from each otheralong the width dimension of the cable. Reducing the number of drainwires also simplifies manufacturing by reducing the number ofconnections needed between the cable and the termination component, thusalso reducing the number of fabrication steps and reducing the timeneeded for fabrication.

Furthermore, by using fewer drain wires, the drain wire(s) that remaincan be positioned farther apart from the nearest signal wire than isnormal so as to make the termination process significantly easier withonly a slight increase in cable width. For example, a given drain wiremay be characterized by a spacing al from a center of the drain wire toa center of a nearest insulated wire of a nearest conductor set, and thenearest conductor set may be characterized by a center-to-center spacingof insulated conductors of σ2; and σ1/σ2 may be greater than 0.7. Incontrast, conventional twinax cable has a drain wire spacing of 0.5times the insulated conductor separation, plus the drain wire diameter.

In exemplary high density embodiments of the disclosed shieldedelectrical ribbon cables, the center-to-center spacing or pitch betweentwo adjacent twinax pairs (which distance is referred to below inconnection with FIG. 16 as Σ) is at least less than four times, andpreferably less than 3 times, the center-to-center spacing between thesignal wires within one pair (which distance is referred to below inconnection with FIG. 16 as σ). This relationship, which can be expressedas Σ/σ<4 or Σ/σ<3, can be satisfied both for unjacketed cables designedfor internal applications, and jacketed cables designed for externalapplications. As explained elsewhere herein, we have demonstratedshielded electrical ribbon cables with multiple twinax pairs, and havingacceptable loss and shielding (crosstalk) characteristics, in which Σ/σis in a range from 2.5 to 3.

An alternative way of characterizing the density of a given shieldedribbon cable (regardless of whether any of the conductor sets of thecable have a pair of conductors in a twinax configuration) is byreference to the nearest insulated conductors of two adjacent conductorsets. Thus, when the shielded cable is laid flat, a first insulatedconductor of a first conductor set is nearest a second (adjacent)conductor set, and a second insulated conductor of the second conductorset is nearest the first conductor set. The center-to-center separationof the first and second insulated conductors is S. The first insulatedconductor has an outer dimension D1, e.g., the diameter of itsinsulation, and the second insulated conductor has an outer dimensionD2, e.g. the diameter if its insulation. In many cases the conductorsets use the same size insulated conductors, in which case D1=D2. Insome cases, however, D1 and D2 may be different. A parameter Dmin can bedefined as the lesser of D1 and D2. Of course, if D1=D2, thenDmin=D1=D2. Using the design characteristics for shielded electricalribbon cables discussed herein, we are able to fabricate such cables forwhich S/Dmin is in a range from 1.7 to 2.

The close packing or high density can be achieved in part by virtue ofone or more of the following features of the disclosed cables: the needfor a minimum number of drain wires, or, stated differently, the abilityto provide adequate shielding for some or all of the connector sets inthe cable using fewer than one drain wire per connector set (and in somecases fewer than one drain wire for every two, three, or four or moreconnector sets, for example, or only one or two drain wires for theentire cable); the high frequency signal isolating structures, e.g.,shielding films of suitable geometry, between adjacent conductor sets;the relatively small number and thickness of layers used in the cableconstruction; and the forming process which ensures proper placement andconfiguration of the insulated conductors, drain wires, and shieldingfilms, and does so in a way that provides uniformity along the length ofthe cable. The high density characteristic can advantageously beprovided in a cable capable of being mass stripped and mass terminatedto a paddle card or other linear array. The mass stripping andtermination is facilitated by separating one, some, or all drain wiresin the cable from their respective closest signal line, i.e. the closestinsulated conductor of the closest conductor set, by a distance greaterthan one-half the spacing between adjacent insulated conductors in theconductor set, and preferably greater than 0.7 times such spacing.

By electrically connecting the drain wires to the shielding films, andproperly forming the shielding films to substantially surround eachconductor set, the shield structure alone can provide adequate highfrequency crosstalk isolation between adjacent conductor sets, and wecan construct shielded ribbon cables with only a minimum number of drainwires. In exemplary embodiments, a given cable may have only two drainwires (one of which may be located at or near each edge of the cable),but only one drain wire is also possible, and more than two drain wiresis of course also possible. By using fewer drain wires in the cableconstruction, fewer termination pads are required on the paddle card orother termination component, and that component can thus be made smallerand/or can support higher signal densities. The cable likewise can bemade smaller (narrower) and can have a higher signal density, sincefewer drain wires are present to consume less ribbon width. The reducednumber of drain wires is a significant factor in allowing the disclosedshielded cables to support higher densities than conventional discretetwinax cables, ribbon cables composed of discrete twinax pairs, andordinary ribbon cables.

Near-end crosstalk and/or far-end crosstalk can be important measures ofsignal integrity or shielding in any electrical cable, including thedisclosed cables and cable assemblies. Grouping signal lines (e.g.twinax pairs or other conductor sets) closer together in a cable and ina termination area tends to increase undesirable crosstalk, but thecable designs and termination designs disclosed herein can be used tocounteract this tendency. The subject of crosstalk in the cable andcrosstalk within the connector can be addressed separately, but severalof these methods for crosstalk reduction can be used together forenhanced crosstalk reduction. To increase high frequency shielding andreduce crosstalk in the disclosed cables, it is desirable to form ascomplete a shield surrounding the conductor sets (e.g. twinax pairs) aspossible using the two shielding films on opposite sides of the cable.It is thus desirable to form the shielding films such that their coverportions, in combination, substantially surround any given conductorset, e.g., at least 75%, or at least 80, 85, or 90%, of the perimeter ofthe conductor set. It is also often desirable to minimize (includingeliminate) any gaps between the shielding films in the pinched zones ofthe cable, and/or to use a low impedance or direct electrical contactbetween the two shielding films such as by direct contact or touching,or electrical contact through one or more drain wires, or using aconductive adhesive between the shielding films. If separate “transmit”and “receive” twinax pairs or conductors are defined or specified for agiven cable or system, high frequency shielding may also be enhanced inthe cable and/or at the termination component by grouping all such“transmit” conductors physically next to each another, and grouping allsuch “receive” conductors next to each other but segregated from thetransmit pairs, to the extent possible, in the same ribbon cable. Thetransmit group of conductors may also be separated from the receivegroup of conductors by one or more drain wires or other isolationstructures as described elsewhere herein. In some cases, two separateribbon cables, one for transmit conductors and one for receiveconductors, may be used, but the two (or more) cables are preferablyarranged in a side-by-side configuration rather than stacked, so thatadvantages of a single flexible plane of ribbon cable can be maintained.

The described shielded cables may exhibit a high frequency isolationbetween adjacent insulated conductors in a given conductor setcharacterized by a crosstalk C1 at a specified frequency in a range from3-15 GHz and for a 1 meter cable length, and may exhibit a highfrequency isolation between the given conductor set and an adjacentconductor set (separated from the first conductor set by a pinchedportion of the cable) characterized by a crosstalk C2 at the specifiedfrequency, and C2 is at least 10 dB lower than C1. Alternatively or inaddition, the described shielded cables may satisfy a shieldingspecification similar to or the same as that used in mini-SASapplications: a signal of a given signal strength is coupled to one ofthe transmit conductor sets (or one of the receive conductor sets) atone end of the cable, and the cumulative signal strength in all of thereceive conductor sets (or in all of the transmit conductor sets), asmeasured at the same end of the cable, is calculated. The near-endcrosstalk, computed as the ratio of the cumulative signal strength tothe original signal strength, and expressed in decibels, is preferablyless than −26 dB.

If the cable ends are not properly shielded, the crosstalk at the cableend can become significant for a given application. A potential solutionwith the disclosed cables is to maintain the structure of the shieldingfilms as close as possible to the termination point of the insulatedconductors, so as to contain any stray electromagnetic fields within theconductor set. Beyond the cable, design details of the paddle card orother termination component can also be tailored to maintain adequatecrosstalk isolation for the system. Strategies include electricallyisolating transmit and receive signals from each other to the extentpossible, e.g. terminating and routing wires and conductors associatedwith these two signal types as physically far apart from each other aspossible. One option is to terminate such wires and conductors onseparate sides (opposed major surfaces) of the paddle card, which can beused to automatically route the signals on different planes or oppositesides of the paddle card. Another option is to terminate such wires andconductors laterally as far apart as possible to laterally separatetransmit wires from receive wires. Combinations of these strategies canalso be used for further isolation. (Reference in this regard is made topreviously cited “Connector Arrangements for Shielded Electrical Cable”(Attorney Docket 66887US002), previously incorporated herein byreference.) These strategies can be used with the disclosed high densityribbon cables in combination with paddle cards of conventional size orreduced size, as well as with a single plane of ribbon cable, both ofwhich may provide significant system advantages.

The reader is reminded that the above discussion relating to paddle cardterminations, and discussion elsewhere herein directed to paddle cards,should also be understood as encompassing any other type of termination.For example, stamped metal connectors may include linear arrays of oneor two rows of contacts to connect to a ribbon cable. Such rows may beanalogous to those of a paddle card, which may also include two lineararrays of contacts. The same staggered, alternating, and segregatedtermination strategies for the disclosed cables and terminationcomponents can be employed.

Loss or attenuation is another important consideration for manyelectrical cable applications. One typical loss specification for highspeed I/O applications is that the cable have a loss of less than −6 dBat, for example, a frequency of 5 GHz. (In this regard, the reader willunderstand that, for example, a loss of −5 dB is less than a loss of −6dB.) Such a specification places a limit on attempting to miniaturize acable simply by using thinner wires for the insulated conductors of theconductor sets and/or for the drain wires. In general, with otherfactors being equal, as the wires used in a cable are made thinner,cable loss increases. Although plating of wire, e.g., silver plating,tin plating, or gold plating, can have an impact on cable loss, in manycases, wire sizes smaller than about 32 gauge (32 AWG) or slightlysmaller, whether of solid core or stranded wire design, may represent apractical lower size limit for signal wires in some high speed I/Oapplications. However, smaller wire sizes may be feasible in other highspeed applications, and advances in technology can also be expected torender smaller wire sizes acceptable.

Turning now to FIG. 30 a, we see there a cable system 11401 whichincludes a shielded electrical ribbon cable 11402 in combination with atermination component 11420 such as a paddle card or the like. The cable11402, which may have any of the design features and characteristicsshown and described elsewhere herein, is shown to have eight conductorsets 11404 and two drain wires 11412, each of which is disposed at ornear a respective edge of the cable. Each conductor set is substantiallya twinax pair, i.e., each includes only two insulated conductors 11406,each conductor set preferably being tailored to transmit and/or receivehigh speed data signals. Of course, other numbers of conductor sets,other numbers of insulated conductors within a given conductor set, andother numbers of drain wires (if any) can in general be used for thecable 11402. Eight twinax pairs are however of some significance due tothe existing prevalence of paddle cards designed for use with four“lanes” or “channels”, each lane or channel having exactly one transmitpair and exactly one receive pair. The generally flat or planar designof the cable, and its design characteristics, allow it to be readilybent or otherwise manipulated as shown while maintaining good highfrequency shielding of the conductor sets and acceptable losses. Thenumber of drain wires (2) is substantially less than the number ofconductor sets (8), allowing the cable 11402 to have a substantiallyreduced width w1. Such a reduced width may be realized even in caseswhere the drain wires 11412 are spaced relative to the nearest signalwire (nearest insulated conductor 11406) by at least 0.7 times thespacing of signal wires in the nearest conductor set, since only twodrain wires (in this embodiment) are involved.

The termination component 11420 has a first end 11420 a and an opposedsecond end 11420 b, and a first major surface 11420 c and an opposedsecond major surface 11420 d. Conductive paths 11421 are provided, e.g.by printing or other conventional deposition process(es) and/or etchingprocess(es), on at least the first major surface 11420 c of thecomponent 11420. In this regard, the conductive paths are disposed on asuitable electrically insulating substrate, which is typically stiff orrigid but may in some cases be flexible. Each conductive path typicallyextends from the first end 11420 a to the second end 11420 b of thecomponent. In the depicted embodiment, the individual wires andconductors of the cable 11402 are electrically connected to respectiveones of the conductive paths 11421.

For simplicity, each path is shown to be straight, extending from oneend of the component 11420 or substrate to the other on the same majorsurface of the component. In some cases, one or more of the conductivepaths may extend through a hole or “via” in the substrate so that, forexample, one portion and one end of the path resides on one majorsurface, and another portion and the other end of the path resides onthe opposed major surface of the substrate. Also, in some cases, some ofthe wires and conductors of the cable can attach to conductive paths(e.g. contact pads) on one major surface of the substrate, while othersof the wires and conductors can attach to conductive paths (e.g. contactpads) on the opposite major surface of the substrate but at the same endof the component. This may be accomplished by e.g. slightly bending theends of the wires and conductors upward towards one major surface, ordownward towards the other major surface. In some cases, all of theconductive paths corresponding to the signal wires and/or drain wires ofthe shielded cable may be disposed on one major surface of thesubstrate. In some cases, at least one of the conductive paths may bedisposed on one major surface of the substrate, and at least another ofthe conductive paths may be disposed on an opposed major surface of thesubstrate. In some cases, at least one of the conductive paths may havea first portion on a first major surface of the substrate at the firstend, and a second portion on an opposed second major surface of thesubstrate at the second end. In some cases, alternating conductor setsof the shielded cable may attach to conductive paths on opposite majorsurfaces of the substrate.

The termination component 11420 or substrate thereof has a width w2. Inexemplary embodiments, the width w1 of the cable is not significantlylarger than the width w2 of the component so that, for example, thecable need not be folded over or bunched together at its end in order tomake the necessary connections between the wires of the cable and theconductive paths of the component. In some cages w1 may be slightlygreater than w2, but still small enough so that the ends of theconductor sets may be bent in the plane of the cable in a funnel-typefashion in order to connect to the associated conductor paths, whilestill preserving the generally planar configuration of the cable at andnear the connection point. In some cases, w1 may be equal to or lessthan w2. Conventional four channel paddle cards currently have a widthof 15.6 millimeters, hence, it is desirable in at least someapplications for the shielded cable to have a width of about 16 mm orless, or about 15 mm or less.

FIGS. 30 b and 30 c are front cross-sectional views of exemplaryshielded electrical cables, which figures also depict parameters usefulin characterizing the density of the conductor sets. Shielded cable11502 includes at least three conductor sets 11504 a, 11504 b, and 11504c, which are shielded from each other by virtue of first and secondshielding films 11508 on opposite sides of the cable, with theirrespective cover portions, pinched portions, and transition portionssuitably formed. Shielded cable 11602 likewise includes at least threeconductor sets 11604 a, 11604 b, and 11604 c, which are shielded fromeach other by virtue of first and second shielding films 11608. Theconductor sets of cable 11502 contain different numbers of insulatedconductors 11506, with conductor set 11504 a having one, conductor set11504 b having three, and conductor set 11504 c having two (for a twinaxdesign). Conductor sets 11604 a, 11604 b, 11604 c are all of twinaxdesign, having exactly two of the insulated conductors 1606. Althoughnot shown in FIGS. 30 b and 30 c, each cable 11502, 11602 preferablyalso includes at least one and optionally two (or more) drain wires,preferably sandwiched between the shielding films at or near the edge(s)of the cable such as shown in FIG. 1 or FIG. 30 a.

In FIG. 30 b we see some dimensions identified that relate to thenearest insulated conductors of two adjacent conductor sets. Conductorset 11504 a is adjacent conductor set 11504 b. The insulated conductor11506 of set 11504 a is nearest the set 11504 b, and the left-most (fromthe perspective of the drawing) insulated conductor 11506 of set 11504 bis nearest the set 11504 a. The insulated conductor of set 11504 a hasan outer dimension D1 , and the left-most insulated conductor of set11504 b has an outer dimension D2. The center-to-center separation ofthese insulated conductors is S1. If we define a parameter Dmin as thelesser of D1 and D2, then we may specify for a densely packed shieldedcable that S1/Dmin is in a range from 1.7 to 2.

We also see in FIG. 30 b that conductor set 11504 b is adjacentconductor set 11504 c. The right-most insulated conductor 11506 of set11504 b is nearest the set 11504 c, and the left-most insulatedconductor 11506 of set 11504 c is nearest the set 11504 b. Theright-most insulated conductor 11506 of set 11504 b has an outerdimension D3, and the left-most insulated conductor 11506 of set 11504 chas an outer dimension D4. The center-to-center separation of theseinsulated conductors is S3. If we define a parameter Dmin as the lesserof D3 and D4, then we may specify for a densely packed shielded cablethat S3/Dmin is in a range from 1.7 to 2.

In FIG. 30 c we see some dimensions identified that relate to cableshaving at least one set of adjacent twinax pairs. Conductor sets 11604a, 11604 b represent one such set of adjacent twinax pairs. Thecenter-to-center spacing or pitch between these two conductor sets isexpressed as Σ. The center-to-center spacing between signal wires withinthe twinax-conductor set 11604 a is expressed as al. Thecenter-to-center spacing between signal wires within the twinaxconductor set 11604 b is expressed as σ2. For a densely packed shieldedcable, we may specify that one or both of Σ/σ1 and Σ/σ2 is less than 4,or less than 3, or in a range from 2.5 to 3.

In FIGS. 30 d and 30 e, we see a top view and side view respectively ofa cable system 11701 which includes a shielded electrical ribbon cable11702 in combination with a termination component 11720 such as a paddlecard or the like. The cable 11702, which may have any of the designfeatures and characteristics shown and described elsewhere herein, isshown to have eight conductor sets 11704 and two drain wires 11712, eachof which is disposed at or near a respective edge of the cable. Eachconductor set is substantially a twinax pair, i.e., each includes onlytwo insulated conductors 11706, each conductor set preferably beingtailored to transmit and/or receive high speed data signals. Just as inFIG. 30 a, the number of drain wires (2) is substantially less than thenumber of conductor sets (8), allowing the cable 11702 to have asubstantially reduced width relative to a cable having one or two drainwires per conductor set, for example. Such a reduced width may berealized even in cases where the drain wires 11712 are spaced relativeto the nearest signal wire (nearest insulated conductor 11706) by atleast 0.7 times the spacing of signal wires in the nearest conductorset, since only two drain wires (in this embodiment) are involved.

The termination component 11720 has a first end 11720 a and an opposedsecond end 11720 b, and includes a suitable substrate having a firstmajor surface 11720 c and an opposed second major surface 11720 d.Conductive paths 11721 are provided on at least the first major surface11720 c of the substrate. Each conductive path typically extends fromthe first end 11720 a to the second end 11720 b of the component. Theconductive paths are shown to include contact pads at both ends of thecomponent, in the figure the individual wires and conductors of thecable 11702 are shown as being electrically, connected to respectiveones of the conductive paths 11721 at the corresponding contact pad.Note that the variations discussed elsewhere herein regarding placement,configuration, and arrangement of the conductive paths on the substrate,and placement, configuration, and arrangement of the various wires andconductors of the cable and their attached to one or both of the majorsurfaces of the termination component, are also intended to apply to thesystem 11701.

EXAMPLE

A shielded electrical ribbon cable having the general layout of cable11402 (see FIG. 30 a) was fabricated. The cable utilized sixteeninsulated 32 gauge (AWG) wires arranged into eight twinax pairs forsignal wires, and two non-insulated 32 (AWG) wires arranged along theedges of the cable for drain wires. Each of the sixteen signal wiresused had a solid copper core with silver plating. The two drain wireseach had a stranded construction (7 strands each) and were tin-plated.The insulation of the insulated wires had a nominal outer diameter of0.025 inches. The sixteen insulated and two non-insulated wires were fedinto a device similar to that shown in FIG. 5 c, sandwiched between twoshielding films. The shielding films were substantially identical, andhad the following construction: a base layer of polyester (0.00048inches thick), on which a continuous layer of aluminum (0.00028 inchesthick) was disposed, on which a continuous layer of electricallynon-conductive adhesive (0.001 inches thick) was disposed. The shieldingfilms were oriented such that the metal coatings of the films faced eachother and faced the conductor sets. The process temperature was about270 degrees F. The resulting cable made by this process was photographedand is shown in top view in FIG. 30 f, and an oblique view of the end ofthe cable is shown in FIG. 30 g. In the figures, 1804 refers to thetwinax conductor sets, and 1812 refers to the drain wires.

The resulting cable was non-ideal due to lack of concentricity of thesolid core in the insulated conductor used for the signal wires.Nevertheless, certain parameters and characteristics of the cable couldbe measured, taking into account (correcting for) the non-concentricityissue. For example, the dimensions D, d1, d2 (see FIG. 2 c) were about0.028 inches, 0.0015 inches, and 0.028 inches, respectively. No portionof either one of the shielding films had a radius of curvature at anypoint along the width of the cable of less than 50 microns, intransverse cross section. The center-to-center spacing from a givendrain wire to the nearest insulated wire of the nearest twinax conductorset was about 0.83 mm, and the center-to-center spacing of the insulatedwires within each conductor set (see e.g. parameters σ1 and σ2 in FIG.30 c) was about 0.025 inches (0.64 mm). The center-to-center spacing ofadjacent twinax conductor sets (see e.g. the parameter Σ in FIG. 30 c)was about 0.0715 inches (1.8 mm). The spacing parameter S (see S1 and S3in FIG. 30 b) was about 0.0465 inches. The width of the cable, measuredfrom edge to edge, was about 16 to 17 millimeters, and the spacingbetween the drain wires was 15 millimeters. The cable was readilycapable of mass termination, including the drain wires.

From these values we see that: the spacing from the drain wire to thenearest signal wire was about 1.3 times the wire-to-wire spacing withineach twinax pair, thus, greater than 0.7 times the wire-to-wire spacing;the cable density parameter E/a was about 2.86, i.e., in the range from2.5 to 3; the other cable density parameter S/Dmin was about 1.7, i.e.,in the range from 1.7 to 2; the ratio d₁/D (minimum separation of thepinched portions of the shielding films divided by the maximumseparation between the cover portions of the shielding films) was about0.05, i.e., less than 0.25 and also less than 0.1; the ratio d₂/D(minimum separation between the cover portions of the shielding films ina region between insulated conductors divided by the maximum separationbetween the cover portions of the shielding films) was about 1, i.e.,greater than 0.33.

Note also that the width of the cable (i.e., about 16 mm edge-to-edge,and 15.0 mm from drain wire to drain wire) was less than the width of aconventional mini-SAS internal cable outer molding termination(typically 17.1 mm), and about the same as the typical width of amini-SAS paddle card (15.6 mm). A smaller width than the paddle cardallows simple one-to-one routing from the cable to the paddle card withno lateral adjustment of the wire ends needed. Even if the cable wereslightly wider than the termination board or housing, the outer wirecould be routed or bent laterally to meet the pads on the outside edgesof the board. Physically this cable can provide a double density versusother ribbon cables, can be half as thick in an assembly (since one lessribbon is needed), and can allow for a thinner connector than othercommon cables. The cable ends can be terminated and manipulated in anysuitable fashion to connect with a termination component as discussedelsewhere herein.

We now provide further details regarding shielded ribbon cables that canemploy an on-demand drain wire feature.

In many of the disclosed shielded electrical cables, a drain wire thatmakes direct or indirect electrical contact with one or both of theshielding films makes such electrical contact over substantially theentire length of the cable. The drain wire may then be tied to anexternal ground connection at a termination location to provide a groundreference to the shield so as to reduce (or “drain”) any stray signalsthat can produce crosstalk and reduce electromagnetic interference(EMI). In this section of the detailed description, we more fullydescribe constructions and methods that provide electrical contactbetween a given drain wire and a given shielding film at one or moreisolated areas of the cable, rather than along the entire cable length.We sometimes refer to the constructions and methods characterized by theelectrical contact at the isolated area(s) as the on-demand technique.

This on-demand technique may utilize the shielded cables describedelsewhere herein, wherein the cable is made to include at least onedrain, wire that has a high DC electrical resistance between the drainwire and at least one shielding film over all of, or at least over asubstantial portion of, the length of the drain wire. Such a cable maybe referred to, for purposes of describing the on-demand technique, asan untreated cable. The untreated cable can then be treated in at leastone specific localized region in order to substantially reduce the DCresistance and provide electrical contact (whether direct or indirect)between the drain wire and the shielding film(s) in the localizedregion. The DC resistance in the localized region may for example beless than 10 ohms, or less than 2 ohms, or substantially zero ohms.

The untreated cable may include at least one drain wire, at least oneshielding film, and at least one conductor set that includes at leastone insulated conductor suitable for carrying high speed signals. FIG.31 a is a front cross-sectional view of an exemplary shielded electricalcable 11902 which may serve as an untreated cable, although virtuallyany other shielded cable shown or described herein can also be used. Thecable 11902 includes three conductor sets 11904 a, 11904 b, 11904 c,which each include one or more insulated conductors, the cable alsohaving six drain wires 11912 a-f which are shown in a variety ofpositions for demonstration purposes. The cable 11902 also includes twoshielding films 11908 disposed on opposite sides of the cable andpreferably having respective cover portions, pinched portions, andtransition portions. Initially, a non-conductive adhesive material orother compliant non-conductive material separates each drain wire fromone or both shielding films. The drain wire, the shielding film(s), andthe non-conductive material therebetween are configured so that theshielding film can be made to make direct or indirect electrical contactwith the drain wire on demand in a localized or treated region.Thereafter, a suitable treatment process is used to accomplish thisselective electrical contact between any of the depicted drain wires11912 a-f and the shielding films 11908.

FIGS. 31 b, 31 c, and 31 d are front cross-sectional views of shieldedcables or portions thereof that demonstrate at least some such treatmentprocesses. In FIG. 31 ba, a portion of a shielded electrical cable 12002includes opposed shielding films 12008, each of which may include aconductive layer 12008 a and a non-conductive layer 12008 b. Theshielding films are oriented so that the conductive layer of eachshielding film faces a drain wire 12012 and the other shielding film. Inan alternative embodiment, the non-conductive layer of one or bothshielding films may be omitted. Significantly, the cable 12002 includesa non-conductive material (e.g. a dielectric material) 12010 between theshielding films 12008 and that separates the drain wire 12012 from eachof the shielding films 12008. In some cases, the material 12010 may beor comprise a non-conductive compliant adhesive material. In some cases,the material 12010 may be or comprise a thermoplastic dielectricmaterial such as polyolefin at a thickness of less than 0.02 mm, or someother suitable thickness. In some cases, the material 12010 may be inthe form of a thin layer that covers one or both shielding films priorto cable manufacture. In some cases, the material 12010 may be in theform of a thin insulation layer that covers the drain wire prior tocable manufacture (and in the untreated cable), in which case suchmaterial may not extend into the pinched regions of the cable unlike theembodiment shown in FIGS. 31 b and 31 c.

To make a localized connection, compressive force and/or heat may beapplied within a limited area or zone to force the shielding films 12008into permanent electrical contact with the drain wire 12012 byeffectively forcing the material 12010 out of the way. The electricalcontact may be direct or indirect, and may be characterized by a DCresistance in the localized treated region of less than 10 ohms, or lessthan 2 ohms, or substantially zero ohms. (Untreated portions of thedrain wire 12012 continue to be physically separated from the shieldingfilm and would be characterized by a high DC resistance (e.g. >100ohms), except of course for the fact that the untreated portions of thedrain wire electrically connect to the shielding film through thetreated portion(s) of the drain wire.) The treatment procedure can berepeated at different isolated areas of the cable in subsequent steps,and/or can be performed at multiple isolated areas of the cable in anygiven single step. The shielded cable also preferably contains at leastone group of one ore more insulated signal wires for high speed datacommunication. In FIG. 31 d, for example, shielded cable 12102 has aplurality of twinax conductor sets 12104 with shielding provided byshielding films 12108. The cable 12102 includes drain wires 12112, twoof which (12112 a, 12112 b) are shown as being treated in a single step,for example with pressure, heat, radiation, and/or any other suitableagent, using treating components 12130. The treating componentspreferably have a length (a dimension along an axis perpendicular to theplane of the drawing) which is small compared to the length of the cable12102 such that the treated region is similarly small compared to thelength of the cable. The treatment process for on-demand drain wirecontact can be performed (a) during cable manufacture, (b) after thecable is cut to length for termination process, (c) during thetermination process (even simultaneously when the cable is terminated),(d) after the cable has been made into an cable assembly (e.g. byattachment of termination components to both ends of the cable), or (e)any combination of (a) through (d).

The treatment to provide localized electrical contact between the drainwire and one or both shielding films may in some cases utilizecompression. The treatment may be carried out at room temperature withhigh local force that severely deforms the materials and causes contact,or at elevated temperatures at which, for example, a thermoplasticmaterial as discussed above may flow more readily. Treatment may alsoinclude delivering ultrasonic energy to the area in order to make thecontact. Also, the treatment process may be aided by the use ofconductive particles in a dielectric material separating the shieldingfilm and drain wire, and/or with asperities provided on the drain wireand/or shielding film.

FIGS. 31 e and 31 f are top views of a shielded electrical cableassembly 12201, showing alternative configurations in which one maychoose to provide on-demand contact between drain wires and shieldingfilm(s). In both figures, a shielded electrical ribbon cable 12202 isconnected at both ends thereof to termination components 12220, 12222.The termination components each comprise a substrate with individualconductive paths provided thereon for electrical connection to therespective wires and conductors of the cable 12202. The cable 12202includes several conductor sets of insulated conductors, such as twinaxconductor sets adapted for high speed data communication. The cable12202 also includes two drain wires 12212 a, 12212 b. The drain wireshave ends that connect to respective conductive paths of eachtermination component. The drain wires are also positioned near (e.g.covered by) at least one shielding film of the cable, and preferably arepositioned between two such films as shown for example in thecross-sectional views of FIGS. 31 a and 31 b. Except for localizedtreated areas or zones that will be described below, the drain wires12212 a, 12212 b do not make electrical contact with the shieldingfilm(s) at any point along the length of the cable, and this may beaccomplished by any suitable means e.g. by employing any of theelectrical isolation techniques described elsewhere herein: A DCresistance between the drain wires and the shielding film(s) in theuntreated areas may, for example, be greater than 100 ohms. However, thecable is preferably treated at selected zones or areas as describedabove to provide electrical contact between a given drain wire and agiven shielding film(s). In FIG. 31 e, the cable 12202 has been treatedin localized area 12213 a to provide electrical contact between drainwire 12212 a and the shielding film(s), and it has also been treated inlocalized areas 12213 b, 12213 c to provide electrical contact betweendrain wire 12212 b and the shielding film(s). In FIG. 31 f, the cable12202 is shown as being treated in the same localized areas 12213 a and12213 b, but also in different localized areas 12213 d, 2213 e.

Note that in some cases multiple treated areas can be used for a singledrain wire for redundancy or for other purposes. In other cases, only asingle treated area may be used for a given drain wire. In some cases, afirst treated area for a first drain wire may be disposed at a samelengthwise position as a second treated area for a second drain wire—seee.g. areas 12213 a, 12213 b of FIGS. 31 e, 31 f, and see also theprocedure shown in FIG. 31 d. In some cases, a treated area for onedrain wire may be disposed at a different lengthwise position than atreated area for another drain wire—see e.g. areas 12231 a and 12213 cof FIG. 31 e, or areas 12213 d and 12213 e of FIG. 31 f. In some cases,a treated area for one drain wire may be disposed at a lengthwiseposition of the cable at which another drain wire lacks any localizedelectrical contact with the shielding film(s)—see e.g. area 12213 c ofFIG. 31 e, or area 12213 d or area 12213 e of FIG. 31 f.

FIG. 31 g is a top view of another shielded electrical cable assembly12301, showing another configuration in which one may choose to provideon-demand contact between drain wires and shielding film(s). In assembly12301, a shielded electrical ribbon cable 12302 is connected at bothends thereof to termination components 12320, 12322. The terminationcomponents each comprise a substrate with individual conductive pathsprovided thereon for electrical connection to the respective wires andconductors of the cable 12302. The cable 12302 includes severalconductor sets of insulated conductors, such as twinax conductor setsadapted for high speed data communication. The cable 12302 also includesseveral drain wires 12312 a-d. The drain wires have ends that connect torespective conductive paths of each termination component. The drainwires are also positioned near (e.g. covered by) at least one shieldingfilm of the cable, and preferably are positioned between two such filmsas shown for example in the cross-sectional views of FIGS. 31 a and 31b. Except for localized treated areas or zones that will be describedbelow, at least the drain wires 112312 a, 112312 d do not makeelectrical contact with the shielding film(s) at any point along thelength of the cable, and this may be accomplished by any suitable meanse.g. by employing any of the electrical isolation techniques describedelsewhere herein. A DC resistance between these drain wires and theshielding film(s) in the untreated areas may, for example, be greaterthan 100 ohms. However, the cable is preferably treated at selectedzones or areas as described above to provide electrical contact betweenthese drain wires and a given shielding film(s). In the figure, thecable 12302 is shown to be treated in localized area 12313 a to provideelectrical contact between drain wire 12312 a and the shielding film(s),and is also shown to be treated in localized areas 12313 b, 12313 c toprovide electrical contact between drain wire 2312 d and the shieldingfilm(s). One or both of the drain wires 12313 b, 12312 c may be of thetype that are suitable for localized treatment, or one or both may bemade in a more standard manner in which they make electrical contactwith the shielding film(s) along substantially their entire lengthduring cable manufacture.

EXAMPLES

Two examples are presented in this section. First, two substantiallyidentical untreated shielded electrical ribbon cables were made with thesame number and configuration of conductor sets and drain wires as theshielded cable shown in FIG. 31 d. Each cable was made using two opposedshielding films having the same construction: a base layer of polyester(0.00048 inches thick), on which a continuous layer of aluminum (0.00028inches thick) was disposed, on which a continuous layer of electricallynon-conductive adhesive (0.001 inch thick) was, disposed. The eightinsulated conductors used in each cable to make the four twinaxconductor sets were 30 gauge (AWG), solid core, silver plated copperwire. The eight drain wires used for each cable were 32 gauge (AWG),tin-plated, 7-stranded wires. The settings used for the manufacturingprocess were adjusted so that a thin layer (less than 10 micrometers) ofthe adhesive material (a polyolefin) remained between each drain wireand each shielding film to prevent electrical contact therebetween inthe untreated cables. The two untreated cables were each cut to a lengthof about 1 meter, and were mass stripped at one end.

A first one of these untreated cables was initially tested to determineif any of the drain wires were in electrical contact with either of theshielding films. This was done by connecting a micro-ohmmeter at thestripped end of the cable to all 28 possible combinations of two drainwires. These measurements yielded no measurable DC resistance for any ofthe combinations—i.e., all combinations produced DC resistances wellover 100 ohms. Then, two adjacent drain wires, as depicted in FIG. 31 d,were treated in one step to provide localized areas of contact betweenthose drain wires and the two shielding films. Another two adjacentdrain wires, e.g., the two adjacent wires labeled 12112 at the left sideof FIG. 31 d, were also treated in the same way in a second step. Eachtreatment was accomplished by compressing a portion of the cable with atool that was about 0.25 inches long and 0.05 inches wide, the toolwidth covering two adjacent drain wires at one lengthwise position ofthe cable. Each treated portion was about 3 cm from one end of thecable. In this first example, the tool temperature was 220 degrees C.,and a force of about 75-150 pounds was applied for 10 seconds for eachtreatment. The tool was then removed and the cable allowed to cool. Themicro-ohmmeter was then connected at the end of the cable opposite thetreated end, and all 28 possible combinations of two drain wires wereagain tested. The DC resistance of one pair (two of the treated drainwires) was measured as 1.1 ohms, and the DC resistance of all othercombinations of two drain wires (measured at the end of the cableopposite the treated end) was not measurable, i.e., was well over 100ohms.

The second one of the untreated cables was also initially tested todetermine if any of the drain wires were in electrical contact witheither of the shielding films. This was again done by connecting amicro-ohmmeter at the stripped end of the cable to all 28 possiblecombinations of two drain wires, and the measurements again yielded nomeasurable DC resistance for any of the combinations—i.e., allcombinations produced DC resistances well over 100 ohms. Then, twoadjacent drain wires, as depicted in FIG. 21, were treated in a firststep to provide localized areas of contact between those drain wires andthe two shielding films. This treatment was done with the same tool asin example 1, and the treated portion was about 3 cm from a first end ofthe cable. In a second treatment step, the same two drain wires weretreated under the same conditions as the first step, but at a position 3cm from a second end of the cable opposite the first end. In a thirdstep, another two adjacent drain wires, e.g., the two adjacent wireslabeled 12112 at the left side of FIG. 31 d, were treated in the sameway as the first step, again 3 cm from the first end of the cable. In afourth treatment step, the same two drain wires treated in step 3 weretreated under the same conditions, but at a treatment location 3 cm fromthe second end of the cable. In this second example, the tooltemperature was 210 degrees C., and a force of about 75-150 pounds wasapplied for 10 seconds for each treatment step. The tool was thenremoved and the cable allowed to cool. The micro-ohmmeter was thenconnected at one end of the cable, and all 28 possible combinations oftwo drain wires were attain tested. An average DC resistance of 0.6 ohmswas measured for five of the combinations (all five of thesecombinations involving the four drain wires having treated areas), and aDC resistance of 21.5 ohms was measured as for the remaining combinationinvolving the four drain wires having treated areas. The DC resistanceof all other combinations of two drain wires was not measurable, i.e.,was well over 100 ohms.

FIG. 32 a is a photograph of one of the shielded electrical cables thatwas fabricated and treated for these examples. Four localized treatedareas can be seen. FIG. 32 b is an enlarged detail of a portion of FIG.32 a, showing two of the localized treated areas. FIG. 32 c is aschematic representation of a front elevational view of the frontcross-sectional layout of the cable of FIG. 32 a.

We now provide further details regarding shielded ribbon cables that canemploy multiple drain wires, and unique combinations of such cables withone or more termination components at one or two ends of the cable.

Conventional coaxial or twinax cable uses multiple independent groups ofwires, each with their own drain wires to make ground connection betweenthe cable and the termination point. An advantageous aspect of theshielded cables described herein is that they can include drain wires inmultiple locations throughout the structure, as was shown e.g. in FIG.31 a. Any given drain wire can be directly (DC) connected to the shieldstructure, AC connected to the shield (low impedance AC connection), orcan be poorly or not connected at all to the shield (high AC impedance).Because the drain wires are elongated conductors, they can extend beyondthe shielded cable and make connection to the ground termination of amating connector. An advantage of the disclosed cables is that ingeneral fewer drain wires can be used in some applications since theelectrical shields provided by the shielding films are common for theentire cable structure.

We have found that one can use the disclosed shielded cables toadvantageously provide a variety of different drain wire configurationsthat can interconnect electrically through the conductive shield of theshielded ribbon cable. Stated simply, any of the disclosed shieldedcables may include at least a first and second drain wire. The first andsecond drain wires may extend along the length of the cable, and may beelectrically connected to each other at least as a result of both ofthem being in electrical contact with a first shielding film. This cablemay be combined with one or more first termination components at a firstend of the cable and one or more second termination components at asecond end of the cable. In some cases, the first drain wire mayelectrically connect to the one or more first termination components butmay not electrically connect to the one or more second terminationcomponents. In some cases, the second drain wire may electricallyconnect to the one or more second termination components but may notelectrically connect to the one or more first termination components.

The first and second drain wires may be members of a plurality of drainwires extending along the length of the cable, and a number n1 of thedrain wires may connect to the one or more first termination components,and a number n2 of the drain wires may connect to the one or more secondtermination components. The number n1 may not be equal to n2.Furthermore, the one or more first termination components maycollectively have a number m1 of first termination components, and theone or more second termination components may collectively have a numberm2 of second termination components. In some cases, n2>n1, and m2>m1. Insome cases, m1=1. In some cases, m1=m2. In some cases, m1<m2. In somecases, m1>1 and m2>1.

Arrangements such as these provides the ability to connect one drainwire to an external connection and have one or more other drain wires beconnected only to the common shield, thereby effectively tying all ofthem to the external ground. Thus, advantageously, not all drain wiresin the cable need to connected to the external ground structure, whichcan be used to simplify the connection by requiring fewer matingconnections at the connector. Another potential advantage is thatredundant contacts can be made if more than one of the drain wire isconnected to the external ground and to the shield. In such cases, onemay fail to make contact to the shield or the external ground with onedrain wire, but still successfully make electrical contact between theexternal ground and the shield through the other drain wire. Further, ifthe cable assembly has a fan-out configuration, wherein one end of thecable is connected to one external connector (m1=1) and common ground,and the other end is tied to multiple connectors (m2>1), then fewerconnections (n1) can be made on the common end than are used (n2) forthe multiple connector ends. The simplified grounding offered by suchconfigurations may provide benefits in terms of reduced complexity andreduced number of contact pads required at the terminations.

In many of these arrangements, the unique interconnected nature of thedrain wires through the shielding film(s), provided of course all of thedrain wires at issue are in electrical contact with the shieldingfilm(s), is used to simplify the termination structure and can provide atighter (narrower) connection pitch. One straightforward embodiment iswhere a shielded cable that includes high speed conductor sets andmultiple drain wires is terminated at both ends to one connector at eachend, and fewer than all of the drain wires are terminated at each end,but each drain wire terminated at one end is also terminated at theother end. The drain wires that are not terminated are still maintainedat low potential since they are also directly or indirectly tied toground. In a related embodiment, one of the drain wires may be connectedat one end but not connected (either intentionally or in error) at theother end. Again in this situation, the ground structure is maintainedas long as one drain wire is connected at each end. In another relatedembodiment, the drain wire(s) attached at one end are not the same asthe drain wire(s) that are attached at the other end. A simple versionof this is depicted in FIG. 32 d. In that figure, a cable assembly 12501includes a shielded electrical cable 12502 connected at one end to atermination component 12520 and connected at the other end to atermination component 12522. The cable 12502 may be virtually anyshielded cable shown or described herein, so long as it includes a firstdrain wire 12512 a and a second drain wire 12512 b that are bothelectrically connected to at least one shielding film. As shown, thedrain wire 12512 b connects to component 12520 but not to component12522, and drain wire 12512 a connects to component 12522 but not tocomponent 12520. Since the ground potential (or other controlledpotential) is shared among the drain wires 12512 a, 12512 b and theshielding film of the cable 12502 by virtue of their mutual electricalconnections, the same potential is maintained in the structure due tothe common grounding. Note that both termination components 12520, 12522could advantageously be made smaller (narrower) by eliminating theunused conduction path.

A more complex embodiment demonstrating these techniques is shown inFIGS. 32 e-32 f. In those figures, a shielded cable assembly 12601 has afan-out configuration. The assembly 12601 includes a shielded electricalribbon cable 12602 connected at a first end to a termination component12620, and connected at a second end (which is split into three separatefan-out sections) to termination components 12622, 12624, 12626. As bestseen in the cross-sectional view of FIG. 32 e, taken along lines 32 g-32g of FIG. 32 e, the cable 12602 includes three conductor sets ofinsulated conductors, one coaxial type and two twinax types, and eightdrain wires 12612 a-h. The eight drain wires are all electricallyconnected to at least one, and preferably two shielding films in thecable 12602. The coaxial conductor set connects to termination component12626, one twinax conductor set connects to termination component 12624,and the other twinax conductor set connects to termination component12622, and all three conductor sets connect to the termination component12620 at the first end of the cable. All eight of the drain wires may beconnected to the termination components at the second end of the cable,i.e., drain wires 12612 a, 12612 b, and 12612 c may be connected toappropriate conductive paths on termination component 12626, and drainwires 12612 d and 12612 e may be connected to appropriate conductivepaths on termination component 12624, and drain wires 12612 f and 12612g may be connected to appropriate conductive paths on terminationcomponent 12622. Advantageously, however, less than all eight of thedrain wires can be connected to the termination component 12620 at thefirst end of the cable. In the figure, only drain wires 12612 a and12612 h are shown as being connected to appropriate conductive paths onthe component 12620. By omitting termination connections between thedrain wires 12612 b-g and termination component 12620, the manufactureof the assembly 12601 is simplified and streamlined. Yet, for example,the drain wires 12612 d and 12612 e adequately tie the conductive pathsto ground potential (or another desired potential) even though neitherof them is physically connected to the termination component 12620.

With regard to the parameters n1, n2, m1, and m2 discussed above, thecable assembly 12601 has n1=2, n2=8, m1=1, and m2=3.

Another fan-out shielded cable assembly 12701 is shown in FIGS. 33 a-b.The assembly 12701 includes a shielded electrical ribbon cable 12702connected at a first end to a termination component 12720, and connectedat a second end (which is split into three separate fan-out sections) totermination components 12722, 12724, 12726. As best seen in thecross-sectional view of FIG. 33 b, taken along lines 33 b-33 b of FIG.33 a, the cable 12702 includes three conductor sets of insulatedconductors, one coaxial type and two twinax types, and eight drain wires12712 a-h. The eight drain wires are all electrically connected to atleast one, and preferably two shielding films in the cable 12702. Thecoaxial conductor set connects to termination component 12726, onetwinax conductor set connects to termination component 12724, and theother twinax conductor set connects to termination component 12722, andall three conductor sets connect to the termination component 12720 atthe first end of the cable. Six of the drain wires may be connected tothe termination components at the second end of the cable, i.e., drainwires 12712 b and 12712 c may be connected to appropriate conductivepaths on termination component 12726, and drain wires 12712 d and 12712e may be connected to appropriate conductive paths on terminationcomponent 2724, and drain wires 12712 f and 12712 g may be connected toappropriate conductive paths on termination component 12722. None ofthose six drain wires are connected to the termination component 12720on the first end of the cable. At the first end of the cable, the othertwo drain wires, i.e., drain wires 12712 a and 12712 h, are connected toappropriate conductive paths on the component 2720. By omittingtermination connections between the drain wires 12712 b-g andtermination component 12720, and between drain wire 12712 a andtermination component 2726, and between drain wire 12712 h andtermination component 12722, the manufacture of the assembly 12701 issimplified and streamlined.

With regard to the parameters n1, n2, m1, and m2 discussed above, thecable assembly 12701 has n1=2, n2=6, m1=1, and m2=3.

Many other embodiments are possible, but in general it can beadvantageous to utilize the shield of the cable to connect two separateground connections (conductors) together to ensure that the grounding iscomplete and at least one ground is connected to each terminationlocation at each end of the cable, and more than two for a fanout cable.This means that each drain wire does not need to be connected to eachtermination point. If more than one drain wire is connected at any end,then the connection is made redundant and less prone to failure.

We now provide further details regarding shielded ribbon cables that canemploy mixed conductor sets, e.g., a conductor set adapted for highspeed data transmission and another conductor set adapted for powertransmission or low speed data transmission. Conductor sets adapted forpower transmission or low speed data transmission can be referred to asa sideband.

Some interconnections and defined standards for high speed signaltransmission allow for both high speed signal transmission (providede.g. by twinax or coax wire arrangements) and low speed or powerconductors, both of which require insulation on the conductors. Anexample of this is the SAS standard which defines high speed pairs and“sidebands” included in its mini-SAS 4i interconnection scheme. Whilethe SAS standard indicates sideband usage is outside its scope andvendor-specific, a common sideband use is a SGPIO (Serial GeneralPurpose Input Output) bus, as described in industry specificationSFF-8485. SGPIO has a clock rate of only 100 kHz, and does not requirehigh performance shielded wire.

This section therefore focuses on aspects of cables that are tailored totransmit both high speed signals and low speed signals (or powertransmission), including cable configuration, termination to a linearcontact array, and the termination component (e.g. paddle card)configuration. In general, the shielded electronic ribbon-like cablesdiscussed elsewhere herein can be used with slight modification.Specifically, the disclosed shielded cables can be modified to includeinsulated wires in the construction that are suitable for low speedsignal transmission but not high speed signal transmission, in additionto the conductor sets that are adapted for high speed data transmission,and the drain/ground wires that may also be included. The shielded cablemay thus include at least two sets of insulated wires that carry signalswhose data rates are significantly different. Of course, in the case ofa power conductor, the line does not have a data rate. We also disclosetermination components for the combination high speed/low speed shieldedcables in which conductive paths for the low speed conductors arere-routed between opposite ends of the termination component, e.g.,between the termination end and a connector mating end.

Stated differently, a shielded electrical cable may include a pluralityof conductor sets and a first shielding film. The plurality of conductorsets may extend along a length of the cable and be spaced apart fromeach other along a width of the cable, each conductor set including oneor more insulated conductors. The first shielding film may include coverportions and pinched portions arranged such that the cover portionscover the conductor sets and the pinched portions are disposed atpinched portions of the cable on each side of each conductor set. Theplurality of conductor sets may include one or more first conductor setsadapted for high speed data transmission and one or more secondconductor sets adapted for power transmission or low speed datatransmission.

The electrical cable may also include a second shielding film disposedon an opposite side of the cable from the first shielding film. Thecable may include a first drain wire in electrical contact with thefirst shielding film and also extending along the length of the cable.The one or more first conductor sets may include a first conductor setcomprising a plurality of first insulated conductors having acenter-to-center spacing of σ1, and the one or more second conductorsets may include a second conductor set comprising a plurality of secondinsulated conductors having, a center-to-center spacing of σ2, and σ1may be greater than σ2. The insulated conductors of the one or morefirst conductor sets may all be arranged in a single plane when thecable is laid flat. Furthermore, the one or more second conductor setsmay include a second conductor set having a plurality of the insulatedconductors in a stacked arrangement when the cable is laid flat. The oneor more first conductor sets may be adapted for maximum datatransmission rates of at least 1 Gbps (i.e., about 0.5 GHz), up to e.g.25 Gbps (about 12.5 GHz) or more, or for a maximum signal frequency ofat least 1 GHz, for example, and the one or more second conductor setsmay be adapted for maximum data transmission rates that are less than 1Gbps (about 0.5 GHz), or less than 0.5 Gbps (about 250 MHz), forexample, or for a maximum signal frequency of less than 1 GHz or 0.5GHz, for example. The one or more first may be adapted for maximum datatransmission rates of at least 3 Gbps (about 1.5 GHz).

Such an electrical cable may be combined with a first terminationcomponent disposed at a first end of the cable. The first terminationcomponent may include a substrate and a plurality of conductive pathsthereon, the plurality of conductive paths having respective firsttermination pads arranged on a first end of the first terminationcomponent. The shielded conductors of the first and second conductorsets may connect to respective ones of the first termination pads at thefirst end of the first termination component in an ordered arrangementthat matches an arrangement of the shielded conductors in the cable. Theplurality of conductive paths may have respective second terminationpads arranged on a second end of the first termination component thatare in a different arrangement than that of the first termination padson the first end.

The conductor set(s) adapted for power transmission and/or lower speeddata transmission may include groups of, or individual, insulatedconductors that do not necessarily need to be shielded from one another,do not necessarily require associated ground or drain wires, and may notneed to have a specified impedance. The benefit of incorporating themtogether in a cable having high speed signal pairs is that they can bealigned and terminated in one step. This differs from conventionalcables, which require handling several wire groups without the automaticalignment to a paddle card, for example. The simultaneous stripping andtermination process (to a linear array on a single paddle card or lineararray of contacts) for both the low speed signals and the high speedsignals is particularly advantageous, as is the mixed signal wire cableitself.

FIGS. 33 c-f are front cross-sectional views of exemplary shieldedelectrical cables 12802 a, 12802 b, 12802 c, and 12802 d that canincorporate the mixed signal wire feature. Each of the embodimentspreferably include two opposed shielding films as discussed elsewhereherein, with suitable cover portions and pinched portions, and someshielded conductors grouped into conductor sets adapted for high speeddata transmission (see conductor sets 12804 a), and some shieldedconductors grouped into conductor sets adapted for low speed datatransmission or power transmission (see conductor sets 12804 b, 12804c). Each embodiment also preferably includes one or more drain wires12812. The high speed conductor sets 12804 a are shown as twinax pairs,but other configurations are also possible as discussed elsewhereherein. The lower speed insulated conductors are shown as being smaller(having a smaller diameter or transverse dimension) than the high speedinsulated conductors, since the former conductors may not need to have acontrolled impedance. In alternative embodiments it may be necessary oradvantageous to have a larger insulation thickness around the low speedconductors compared to the high speed conductors in the same cable.However, since space is often at a premium, it is usually desirable tomake the insulation thickness as small as possible. Note also that wiregauge and plating may be different for the low speed lines compared tothe high speed lines in a given cable. In FIGS. 33 c-f, the high speedand low speed insulated conductors are all arranged in a single plane.In such configurations, it can be advantageous to group multiple lowspeed insulated conductors together in a single set, as in conductor set12804 b, to maintain as small a cable width as possible.

When grouping the low speed insulated conductors into sets, theconductors need not be disposed in exactly the same geometrical plane inorder for the cable to retain a generally planar configuration. Shieldedcable 12902 of FIG. 33 g, for example; utilizes low speed insulatedconductors stacked together in a compact space to form conductor set12904 b, the cable 12902 also including high speed conductor sets 12904a and 12904 c. Stacking the low speed insulated conductors in thismanner helps provide a compact and narrow cable width, but may notprovide the advantage of having the conductors lined up in an orderlylinear fashion (for mating with a linear array of contacts on atermination component) after mass termination. The cable 12902 alsoincludes opposed shielding films 12908 and drain wires 12912, as shown.In alternative embodiments involving different numbers of low speedinsulated conductors, stacking arrangements for the low speed insulatedconductors such as shown in sets 12904 d-h of FIG. 33 h may also beused.

Another aspect of mixed signal wire shielded cable relates totermination components used with the cables. In particular, conductorpaths on a substrate of the termination component can be configured tore-route low speed signals from one arrangement on one end of thetermination component (e.g. a termination end of the cable) to adifferent arrangement on an opposite end of the component (e.g. a matingend for a connector). The different arrangement may for example comprisea different order of contacts or of conductor paths on one end relativeto another end of the termination component. The arrangement on thetermination end of the component may be tailored to match the order orarrangement of conductors in the cable, while the arrangement on anopposite end of the component may be tailored to match a circuit boardor connector arrangement different from that of the cable.

The re-routing may be accomplished by utilizing any suitable technique,including in exemplary embodiments using one or more vias in combinationwith a multi-layer circuit board construction to transition a givenconductive path from a first layer to at least a second layer in theprinted circuit board, and then optionally transitioning back to thefirst layer. Some examples are shown in the top views of FIGS. 34 a and34 b.

In FIG. 34 a, a cable assembly 13001 a includes a shielded electricalcable 13002 connected to a termination component 13020 such as a paddlecard or circuit board, having a substrate and conductive paths(including e.g. contact pads) formed thereon. The cable 13002 includesconductor sets 13004 a, e.g. in the form of twinax pairs, adapted forhigh speed data communication. The cable 13002 also includes a sidebandcomprising a conductor set 13004 b adapted for low speed data and/orpower transmission, the conductor set 13004 b having four insulatedconductors in this embodiment. After the cable 13002 has been massterminated, the conductors of the various conductor sets have conductorends that are connected (e.g. by soldering) to respective ends (e.g.contact pads) of the conductive paths on the termination component13020, at a first end 31020 a of the component. The contact pads orother ends of the conductive paths corresponding to the sideband of thecable are labeled 13019 a, 13019 b, 13019 c, 13019 d, and they arearranged in that order from top to bottom of the termination component13020 (although other contact pads, associated with high speedconductors, are present above and below the sideband contact pads on thefirst end 13020 a). The conductive paths for the sideband contact pads13019 a-d, which are shown only schematically in the figure, utilizevias and/or other patterned layers of the component 13020 as needed toconnect contact pad 13019 a to contact pad 13021 a on the second end13020 b of the component, and to connect contact pad 13019 b to contactpad 13021 b on the second end 13020 b of the component, and to connectcontact pad 13019 c to contact pad 13021 c on the second end 13020 b ofthe component, and to connect contact pad 13019 d to contact pad 13021 don the second end 13020 b of the component. In this way, conductor pathson the termination component are configured to re-route low speedsignals from conductor set 13004 b from one arrangement (a-b-c-d) on oneend 13020 a of the termination component to a different arrangement(d-a-c-b) on the opposite end 13020 b of the component.

FIG. 34 b shows a top view of an alternative cable assembly 13001 b, andsimilar reference numerals are used to identify the same or similarparts. In FIG. 34 b, the cable 13002 is mass terminated and connected toa termination component 13022 which is similar in design to terminationcomponent 13020 of FIG. 34 a. Like component 13020, component 13022includes contact pads or other ends of conductive paths corresponding tothe sideband of the cable 13002, the contact pads being labeled 13023 a,13023 b, 13023 c, 13023 d, and they are arranged in that order from topto bottom of the termination component 13022 (although other contactpads, associated with high speed conductors of the cable, are presentabove and below the sideband contact pads on the first end 13022 a ofthe component 13022). The conductive paths for the sideband contact pads13023 a-d are again shown only schematically in the figure. They utilizevias and/or other patterned layers of the component 13022 as needed toconnect contact pad 13023 a to contact pad 13025 a on the second end13022 b of the component, and to connect contact pad 13023 b to contactpad 13025 b on the second end 13022 b of the component, and to connectcontact pad 13023 c to contact pad 13025 c on the second end 13022 b ofthe component, and to connect contact pad 13023 d to contact pad 13025 don the second end 13022 b of the component. In this way, conductor pathson the termination component are configured to re-route low speedsignals from conductor set 3004 b from one arrangement (a-b-c-d) on oneend 13022 a of the termination component to a different arrangement(a-c-b-d) on the opposite end 13022 b of the component.

The cable assemblies of FIGS. 34 a and 34 b are similar to each otherinsofar as, in both cases, the termination component physicallyre-routes conductive paths for low speed signals across other conductivepaths for other low speed signals, but not across any conductive pathsfor high speed signals. In this regard, it is usually not desirable toroute low speed signals across a high speed signal path in order tomaintain a high quality high speed signal. In some circumstances,however, with proper shielding (e.g. a many layer circuit board andadequate shielding layers), this may be accomplished with limited signaldegradation in the high speed signal path as shown in FIG. 34 c. There,a shielded electrical cable 13102, which has been mass terminated,connects to a termination component 13120. The cable 13102 includesconductor sets 13104 a, e.g. in the form of twinax pairs, adapted forhigh speed data communication. The cable 13102 also includes a sidebandcomprising a conductor set 13104 b adapted for low speed data and/orpower transmission, the conductor set 13004 b having one insulatedconductor in this embodiment. After the cable 13102 has been massterminated, the conductors of the various conductor sets have conductorends that are connected (e.g. by soldering) to respective ends (e.g.contact pads) of the conductive paths on the termination component13120, at a first end 13120 a of the component. The contact pad or otherend of the conductive path corresponding to the sideband of the cable islabeled 13119 a, and it is arranged immediately above (from theperspective of FIG. 34 c) contact pads for the middle one of theconductor sets 13104 a. The conductive path for the sideband contact pad13119 a, which is shown only schematically in the figure, utilizes viasand/or other patterned layers of the component 13120 as needed toconnect contact pad 13119 a to contact pad 13121 a on the second end13120 b of the component. In this way, conductor paths on thetermination component are configured to re-route a low speed signal fromconductor set 13104 b from one arrangement (immediately above the middleone of conductor sets 13104 a) on one end 13120 a of the terminationcomponent to a different arrangement (immediately below the contact padsfor the middle one of conductor sets 13104 a) on the opposite end 13120b of the component.

A mixed signal wire shielded electrical cable having the general designof cable 12802 a in FIG. 33 c was fabricated. As shown in FIG. 33 c, thecable included four high speed twinax conductor sets and one low speedconductor set disposed in the middle of the cable. The cable was madeusing 30 gauge (AWG) silver-plated wires for the high speed signal wiresin the twinax conductor sets, and 30 gauge (AWG) tin-plated wires forthe low speed signal wire in the low speed conductor set. The outsidediameter (OD) of the insulation used for the high speed wires was about0.028 inches, and the OD of the insulation used for the low speed wireswas about 0.022 inches. A drain wire was also included along each edgeof the cable as shown in FIG. 33 c. The cable was mass stripped, andindividual wire ends were soldered to corresponding contacts on amini-SAS compatible paddle card. In this embodiment, all conductivepaths on the paddle card were routed from the cable end of the paddlecard to the opposite (connector) end without crossing each other, suchthat the contact pad configuration was the same on both ends of thepaddle card. A photograph of the resulting terminated cable assembly isshown in FIG. 34 d.

In reference now to FIGS. 35 a and 35 b, respective perspective andcross sectional views shows a cable construction according to an exampleembodiment of the invention. Generally, an electrical ribbon cable 20102includes one or more conductor sets 20104. Each conductor set 20104includes two or more conductors (e.g., wires) 20106 extending fromend-to-end along the length of the cable 20102. Each of the conductors20106 is encompassed by a first dielectric 20108 along the length of thecable. The conductors 20106 are affixed to first and second films 20110,20112 that extend from end-to-end of the cable 20102 and are disposed onopposite sides of the cable 20102. A consistent spacing 20114 ismaintained between the first dielectrics 20108 of the conductors 106 ofeach conductor set 20104 along the length of the cable 20102. A seconddielectric 20116 is disposed within the spacing 20114. The dielectric20116 may include an air gap/void and/or some other material.

The spacing 20114 between members of the conductor sets 20104 can bemade consistent enough such that the cable 20102 has equal or betterelectrical characteristics than a standard wrapped twinax cable, alongwith improved ease of termination and signal integrity of thetermination. The films 20110, 20112 may include shielding material suchas metallic foil, and the films 20110, 20112 may be conformably shapedto substantially surround the conductor sets 20104. In the illustratedexample, films 20110, 20112 are pinched together to form flat portions20118 extending lengthwise along the cable 20102 outside of and/orbetween conductor sets 20104. In the flat portions 29118, the films20110, 20112 substantially surround the conductor sets 20104, e.g.,surround a perimeter of the conductor sets 20104 except where a smalllayer (e.g., of insulators and/or adhesives) the films 20110, 20112 joineach other. For example, cover portions of the shielding films maycollectively encompass at least 75%, or at least 80%, or at least 85%,or at least 90%, of the perimeter of any given conductor set. While thefilms 20110, 20112 may be shown here (and elsewhere herein) as separatepieces of film; those of skill in the art will appreciate that the films20110, 20112 may alternatively be formed from a single sheet of film,e.g., folded around a longitudinal path/line to encompass the conductorsets 20104.

The cable 20102 may also include additional features, such as one ormore drain wires 20120. The drain wires 20120 may be electricallycoupled to shielded films 20110, 20112 continually or at discretelocations along the length of the cable 20102. Generally the drain wire20102 provides convenient access at one or both ends of the cable forelectrically terminating (e.g., grounding) the shielding material. Thedrain wire 20120 may also be configured to provide some level of DCcoupling between the films 20110, 20112, e.g., where both films 20110,20112 include shielding material.

In reference now to FIGS. 35 a-e, cross-section diagrams illustratevarious alternate cable construction arrangements, wherein the samereference numbers may be used to indicate analogous components as inother figures. In FIG. 35 c, cable 20202 may be of a similarconstruction as shown in FIGS. 35 a-b, however only one film 20110 isconformably shaped around the conductor sets to form pinched/flatportions 20204. The other film 20112 is substantially planar on one sideof the cable 20202. This cable 20202 (as well as cables 20212 and 20222in FIGS. 35 d-e) uses air in the gaps 20114 as a second dielectricbetween first dielectrics 20108, therefore there is no explicit seconddielectric material 20116 shown between closest points of proximity ofthe first dielectrics 20108. Further, a drain wire is not shown in thesealternate arrangements, but can be adapted to include drain wires asdiscussed elsewhere herein.

In FIGS. 35 d and 35 e, cable arrangements 20212 and 20222 may be of asimilar construction as those previously described, but here both filmsare configured to be substantially planar along the outer surfaces ofthe cables 20212, 20222. In cable 20212, there are voids/gaps 20214between conductor sets 20104. As shown here, these gaps 20214 are largerthan gaps 114 between members of the sets 20104, although this cableconfiguration need not be so limited. In addition to this gap 20214,cable 20222 of FIG. 35 e includes supports/spacers 20224 disposed in thegap 20214 between conductor sets 20104 and or outside of the conductorsets 20104 (e.g., between a conductor set 20104 and a longitudinal edgeof the cable).

The supports 20224 may be fixably attached (e.g., bonded) to films20110, 20112 and assist in providing structural stiffness and/oradjusting electrical properties of the cable 20222. The supports 20224may include any combination of dielectric, insulating, and/or shieldingmaterials for tuning the mechanical and electrical properties of thecable 20222 as desired. The supports 20224 are shown here as circular incross-section, but be configured as having alternate cross sectionalshapes such as ovular and rectangular. The supports 20224 may be formedseparately and laid up with the conductor sets 104 during cableconstruction. In other variations, the supports 20224 may be formed aspart of the films 110, 112 and/or be assembled with the cable 20222 in aliquid form (e.g., hot melt).

The cable constructions 20102, 20202, 20212, 20222 described above mayinclude other features not illustrated. For example, in addition tosignal wires, drain wires, and ground wires, the cable may include oneor more additional isolated wires sometime referred to as sideband.Sideband can be used to transmit power or any other signals of interest.Sideband wires (as well as drain wires) may be enclosed within the films110, 20112 and/or may be disposed outside the films 20110, 20112, e.g.,being sandwiched between the films and an additional layer of material.

The variations described above may utilize various combinations ofmaterials and physical configurations based on the desired cost, signalintegrity, and mechanical properties of the resulting cable. Oneconsideration is the choice of the second dielectric material 20116positioned in the gap 20114 between conductor sets 20104. This seconddielectric may be particular of interest in cases where the conductorsets include a differential pair, are one ground and one signal, and/orare carrying two interfering signals. For example, use of an air gap20114 as a second dielectric may result in a low dielectric constant andlow loss. Use of an air gap 20114 may also have other advantages, suchas low cost, low weight, and increased cable flexibility. However,precision processing may be required to ensure consistent spacing of theconductors that form the air gaps 20114 along a length of the cable.

In reference now to FIG. 35 f, a cross sectional view of a conductor set104 identifies parameters of interest in maintaining a consistentdielectric constant between conductors 20106. Generally, the dielectricconstant of the conductor set 20104 may be sensitive to the dielectricmaterials between the closest points of proximity between the conductorsof the set 20104, as represented here by dimension 20300. Therefore, aconsistent dielectric constant may be maintained by maintaining aconsistent thicknesses 20302 of the dielectric 20108 and consistent sizeof gap 20114 (which may be an air gap or filled with another dielectricmaterial such as dielectric 20116 shown in FIG. 35 a).

It may be desirable to tightly control geometry of coatings of both theconductor 20106 and the conductive film 20110, 20112 in order to ensureconsistent electrical properties along the length of the cable. For thewire coating, this may involve coating the conductor 20106 (e.g., solidwire) precisely with uniform thickness of insulator/dielectric material20108 and ensuring the conductor 20106 is well-centered within thecoating 20108. The thickness of the coating 20108 can be increased ordecreased depending on the particular properties desired for the cable.In some situations, a conductor with no coating may offer optimalproperties (e.g., dielectric constant, easier termination and geometrycontrol), but for some applications industry standards require that aprimary insulation of a minimum thickness is used. The coating 20108 mayalso be beneficial because it may be able to bond to the dielectricsubstrate material 20110, 20112 better than bare wire. Regardless, thevarious embodiments described above may also include a construction withno insulation thickness.

The dielectric 20108 may be formed/coated over the conductors 20106using a different process/machinery than used to assemble the cable. Asa result, during final cable assembly, tight control over variation inthe size of the gap 20114 (e.g., the closest point of proximity betweenthe dielectrics 20108) may be of primary concern to ensure maintainingconstant dielectric constant. Depending on the assembly process andapparatus used, a similar result may be had by controlling a centerlinedistance 304 between the conductors 20106 (e.g., pitch). The consistencyof this may depend on how tightly the outer diameter dimension 20306 ofthe conductors 106 can be maintained, as well as consistency ofdielectric thickness 20302 all around (e.g., concentricity of conductor20106 within dielectric 20108). However, because dielectric effects arestrongest at the area of closest proximity of the conductors 20106, ifthickness 20302 can be controlled at least near the area of closestproximity of adjacent dielectrics 20108, then consistent results may beobtained during final assembly by focusing on controlling the gap size20114.

The signal integrity (e.g., impedance and skew) of the construction maynot only depend on the precision/consistency of placing the signalconductors 20106 relative to each other, but also in precision ofplacing the conductors 106 relative to a ground plane. As shown in FIG.35 f, films 20110 and 20112 include respective shielding and dielectriclayers 20308, 20310. The shielding layer 20308 may act as a ground planein this case, and so tight control of dimension 20312 along the lengthof the cable may be advantageous. In this example, dimension 20312 isshown being the same relative to both the top and bottom films 20110,20112, although it is possible for these distances to be asymmetric insome arrangements (e.g., use of different dielectric 20310thicknesses/constants of films 20110, 20112, or one of the films 20110,20112 does not have the dielectric layer 20310).

One challenge in manufacturing a cable as shown in FIG. 35 f may be totightly control distance 20312 (and/or equivalent conductor to groundplane distances) when the insulated conductors 20106, 20108 are attachedto the conductive film 20110, 20112. In reference now to FIGS. 35 g-h,block diagrams illustrate an example of how consistent conductor toground plane distances may be maintained during manufacture according toan embodiment of the invention. In this example a film (which by way ofexample is designated as film 20112) includes a shielding layer 20308and dielectric layer 20310 as previously described.

To help ensure a consistent conductor to ground plane distance (e.g.,distance 20312 seen in FIG. 35 h) the film 20112 uses a multilayercoated film as the base (e.g., layers 20308 and 20310). A known andcontrolled thickness of deformable material 20320 (e.g., a hot meltadhesive), is placed on the less deformable film base 20308, 20310. Asthe insulated wire 20106, 20108 is pressed into the surface, thedeformable material 20320 deforms until the wire 20106, 20108 pressesdown to a depth controlled by the thickness of deformable material20320, as seen in FIG. 35 h. An example of materials 20320, 20310, 20308may include a hot melt 20320 placed on a polyester backing 20308 or20310, where the other of layers 20308, 20310 includes a shieldingmaterial. Alternatively, or in addition to this, tool features can pressthe insulated wire 20106, 20108 into the film 20112 at a controlleddepth.

In some embodiments described above, an air gap 20114 exists between theinsulated conductors 20106, 20108 at the mid-plane of the conductors.This may be useful in many end applications, include betweendifferential pair lines, between ground and signal lines (GS) and/orbetween victim and aggressor signal lines. An air gap 20114 betweenground and, signal conductors may exhibit similar benefits as describedfor the differential lines, e.g., thinner construction and lowerdielectric constant. For two wires of a differential pair, the air gap20114 can separate the wires, which provides less coupling and thereforea thinner construction than if the gap were not present (providing moreflexibility, lower cost, and less crosstalk). Also, because of the highfields that exist between the differential pair conductors at thisclosest line of approach between them, the lower capacitance in thislocation contributes to the effective dielectric constant of theconstruction.

In reference now to FIG. 36 a, a graph 20400 illustrates an analysis ofconstructions according to an embodiment of the invention. In FIG. 36 b,a block diagram includes geometric features of a conductor set accordingto an example of the invention which will be referred to in discussingFIG. 36 a. Generally, the graph 20400 illustrates differing dielectricconstants obtained for different cable pitch 20304,insulation/dielectric thickness 20302, and cable thickness 20402 (thelatter which may exclude thickness of out shielding layer 20308). Thisanalysis assumes a 26 AWG differential pair conductor set 20104, 100ohms impedance, and solid polyolefin used for insulator/dielectric 20108and dielectric layers 20310. Points 20404 and 20406 are results for 8mil thick insulation at respective 56 and 40 mil thicknesses 20302.Points 20408 and 20410 are results for 1 mil thick insulation atrespective 48 and 38 mil thicknesses 20302. Point 20412 is a result for4.5 mil thick insulation at a 42 mil thickness 20302.

As seen in the graph 20400, thinner insulation around wire tends tolower the effective dielectric constant. If the insulation is very thin,a tighter pitch may then tend to reduce the dielectric constant becauseof the high fields between the wires. If the insulation is thick,however, the greater pitch provides more air around the wires and lowersthe effective dielectric constant. For two signal lines that caninterfere with one another, the air gap is an effective feature forlimiting the capacitive crosstalk between them. If the air gap issufficient, a ground wire may not be needed between signal lines, whichwould result in cost savings.

The dielectric loss and dielectric constant seen in graph 20400 may bereduced by the incorporation of air gaps between the insulatedconductors. The graph 400 reveals that the reduction due to these gapsis on the same order (e.g., 1.6-1.8 for polyolefin materials) as can beachieved a conventional construction that uses a foamed insulationaround the wires. Foamed primary insulation 20108 can also be used inconjunction with the constructions described herein to provide an evenlower dielectric constant and lower dielectric loss. Also, the backingdielectric 20310 can be partially or fully foamed.

A potential benefit of using the engineered air gap 20114 instead offoaming is that foaming can be inconsistent along the conductor 20106 orbetween different conductors 20106 leading to variations in thedielectric constant and propagation delay which increases skew andimpedance variation. With solid insulation 20108 and precise gaps 20114,the effective dielectric constant may be more readily controlled and, inturn, leading to consistency in electrical performance, includingimpedance, skew, attenuation loss, insertion loss, etc.

The cross-sectional views of FIGS. 36 g-37 e may represent variousshielded electrical cables, or portions of cables. Referring to FIG. 36g, shielded electrical cable 21402 c has a single conductor set 21404 cwhich has two insulated conductors 21406 c separated by dielectric gap20114 c. If desired, the cable 21402 c may be made to include multipleconductor sets 21404 c spaced part across a width of the cable 21402 cand extending along a length of the cable. Insulated conductors 21406 care arranged generally in a single plane and effectively in a twinaxialconfiguration. The twin axial cable configuration of FIG. 36 g can beused in a differential pair circuit arrangement or in a single endedcircuit arrangement.

Two shielding films 21408 c are disposed on opposite sides of conductorset 21404 c. The cable 21402 c includes a cover region 21414 c andpinched regions 21418 c. In the cover region 21414 c of the cable 20102c, the shielding films 21408 c include cover portions 21407 c that coverthe conductor set 21404 c. In transverse cross section, the coverportions 21407 c, in combination, substantially surround the conductorset 21404 c. In the pinched regions 21418 c of the cable 21402 c, theshielding films 21408 c include pinched portions 21409 c on each side ofthe conductor set 21404 c.

An optional adhesive layer 21410 c may be disposed between shieldingfilms 21408 c. Shielded electrical cable 21402 c further includesoptional ground conductors 21412 c similar to ground conductors 21412that may include ground wires or drain wires. Ground conductors 21412 care spaced apart from, and extend in substantially the same directionas, insulated conductors 21406 c. Conductor set 21404 c and groundconductors 21412 c can be arranged so that they lie generally in aplane.

As illustrated in the cross section of FIG. 36 g, there is a maximumseparation, D, between the cover portions 21407 c of the shielding films21408 c; there is a minimum separation, d1, between the pinched portions21409 c of the shielding films 21408 c; and there is a minimumseparation, d2, between the shielding films 21408 c between theinsulated conductors 21406 c.

In FIG. 36 g, adhesive layer 21410 c is shown disposed between thepinched portions 21409 c of the shielding films 21408 c in the pinchedregions 21418 c of the cable 20102 c and disposed between the coverportions 21407 c of the shielding films 21408 c and the insulatedconductors 21406 c in the cover region 21414 c of the cable 21402 c. Inthis arrangement, the adhesive layer 21410 c bonds the pinched portions21409 c of the shielding films 21408 c together in the pinched regions21418 c of the cable 21402 c, and also bonds the cover portions 21407 cof the shielding films 21408 c to the insulated conductors 21406 c inthe cover region 21414 c of the cable 21402 c.

Shielded cable 21402 d of FIG. 36 h is similar to cable 21402 c of FIG.36 g, with similar elements identified by similar reference numerals,except that in cable 21402 d the optional adhesive layer 21410 d is notpresent between the cover portions 21407 c of the shielding films 21408c and the insulated conductors 21406 c in the cover region 21414 c ofthe cable. In this arrangement, the adhesive layer 21410 d bonds thepinched portions 21409 c of the shielding films 21408 c together in thepinched regions 21418 c of the cable, but does not bond the coverportions 21407 c of the shielding films 21408 c to the insulatedconductors 1406 c in the cover region 21414 c of the cable 21402 d.

Referring now to FIG. 37 a, we see there a transverse cross-sectionalview of a shielded electrical cable 21402 e similar in many respects tothe shielded electrical cable 21402 c of FIG. 36 g. Cable 21402 eincludes a single conductor set 21404 e that has two insulatedconductors 21406 e separated by dielectric gap 20114 e extending along alength of the cable 21402 e. Cable 21402 e may be made to have multipleconductor sets 21404 e spaced apart from each other across a width ofthe cable 21402 e and extending along a length of the cable 21402 e.Insulated conductors 21406 e are arranged effectively in a twisted paircable arrangement, whereby insulated conductors 21406 e twist aroundeach other and extend along a length of the cable 21402 e.

In FIG. 37 b another shielded electrical cable 21402 f is depicted thatis also similar in many respects to the shielded electrical cable 21402c of FIG. 36 g. Cable 21402 f includes a single conductor set 21404 fthat has four insulated conductors 21406 f extending along a length ofthe cable 21402 f, with opposing conductors being separated by gap 20114f. The cable 21402 f may be made to have multiple conductor sets 21404 fspaced apart from each other across a width of the cable 21402 f andextending along a length of the cable 21402 f. Insulated conductors 1406f are arranged effectively in a quad cable arrangement, wherebyinsulated conductors 21406 f may or may not twist around each other asinsulated conductors 1406 f extend along a length of the cable 21402 f.

Further embodiments of shielded electrical cables may include aplurality of spaced apart conductor sets 21404, 21404 e, or 21404 f, orcombinations thereof, arranged generally in a single plane. Optionally,the shielded electrical cables may include a plurality of groundconductors 21412 spaced apart from, and extending generally in the samedirection as, the insulated conductors of the conductor sets. In someconfigurations, the conductor sets and ground conductors can be arrangedgenerally in a single plane. FIG. 37 c illustrates an exemplaryembodiment of such a shielded electrical cable.

Referring to FIG. 37 c, shielded electrical cable 20102 g includes aplurality of spaced apart conductor sets 21404, 21404 g arrangedgenerally in plane. Conductor sets 21404 g include a single insulatedconductor, but may otherwise be formed similarly to conductor set 21404.Shielded electrical cable 21402 g further includes optional groundconductors 21412 disposed between conductor sets 21404, 21404 g and atboth sides or edges of shielded electrical cable 21402 g.

First and second shielding films 21408 are disposed on opposite sides ofthe cable 21402 g and are arranged so that, in transverse cross section,the cable 21402 g includes cover regions 21424 and pinched regions21428. In the cover regions 21424 of the cable, cover portions 21417 ofthe first and second shielding films 21408 in transverse cross sectionsubstantially surround each conductor set 21404, 21404 g. Pinchedportions 21419 of the first and second shielding films 21408 form thepinched regions 21428 on two sides of each conductor set 21404 g.

The shielding films 21408 are disposed around ground conductors 21412.An optional adhesive layer 21410 is disposed between shielding films21408 and bonds the pinched portions 21419 of the shielding films 21408to each other in the pinched regions 21428 on both sides of eachconductor set 21404, 21404 c. Shielded electrical cable 21402 g includesa combination of coaxial cable arrangements (conductor sets 21404 g) anda twinaxial cable arrangement (conductor set 21404) and may therefore bereferred to as a hybrid cable arrangement.

One, two, or more of the shielded electrical cables may be terminated toa termination component such as a printed circuit board, paddle card, orthe like. Because the insulated conductors and ground conductors can bearranged generally in a single plane, the disclosed shielded electricalcables are well suited for mass-stripping, i.e., the simultaneousstripping of the shielding films and insulation from the insulatedconductors, and mass-termination, i.e., the simultaneous terminating ofthe stripped ends of the insulated conductors and ground conductors,which allows a more automated cable assembly process. This is anadvantage of at least some of the disclosed shielded electrical cables.The stripped ends of insulated conductors and ground conductors may, forexample, be terminated to contact conductive paths or other elements ona printed circuit board, for example. In other cases, the stripped endsof insulated conductors and ground conductors may be terminated to anysuitable individual contact elements of any suitable termination device,such as, e.g., electrical contacts of an electrical connector.

In FIGS. 38 a-38 d an exemplary termination process of shieldedelectrical cable 21502 to a printed circuit board or other terminationcomponent 21514 is shown. This termination process can be amass-termination process and includes the steps of stripping(illustrated in FIGS. 38 a-38 b), aligning (illustrated in FIG. 38 c),and terminating (illustrated in FIG. 38 d). When forming shieldedelectrical cable 21502, which may in general take the form of any of thecables shown and/or described herein, the arrangement of conductor sets21504, 21504 a (with dielectric gap 21520), insulated conductors 21506,and ground conductors 21512 of shielded electrical cable 21502 may bematched to the arrangement of contact elements 1516 on printed circuitboard 21514, which would eliminate any significant manipulation of theend portions of shielded electrical cable 21502 during alignment ortermination.

In the step illustrated in FIG. 38 a, an end portion 21508 a ofshielding films 21508 is removed. Any suitable method may be used, suchas, e.g., mechanical stripping or laser stripping. This step exposes anend portion of insulated conductors 21506 and ground conductors 21512.In one aspect, mass-stripping of end portion 21508 a of shielding films21508 is possible because they form an integrally connected layer thatis separate from the insulation of insulated conductors 21506. Removingshielding films 21508 from insulated conductors 21506 allows protectionagainst electrical shorting at these locations and also providesindependent movement of the exposed end portions of insulated conductors1506 and ground conductors 21512. In the step illustrated in FIG. 38 b,an end portion 21506 a of the insulation of insulated conductors 21506is removed. Any suitable method may be used, such as, e.g., mechanicalstripping or laser stripping. This step exposes an end portion of theconductor of insulated conductors 21506. In the step illustrated in FIG.38 c, shielded electrical cable 21502 is aligned with printed circuitboard 21514 such that the end portions of the conductors of insulatedconductors 21506 and the end portions of ground conductors 21512 ofshielded electrical cable 21502 are aligned with contact elements 21516on printed circuit board 21514. In the step illustrated in FIG. 38 d,the end portions of the conductors of insulated conductors 21506 and theend portions of ground conductors 21512 of shielded electrical cable21502 are terminated to contact elements 21516 on printed circuit board21514. Examples of suitable termination methods that may be used includesoldering, welding, crimping, mechanical clamping, and adhesivelybonding, to name a few.

In FIGS. 39 a-39 c are cross sectional views of three exemplary shieldedelectrical cables, which illustrate examples of the placement of groundconductors in the shielded electrical cables. An aspect of a shieldedelectrical cable is proper grounding of the shield, and such groundingcan be accomplished in a number of ways. In some cases, a given groundconductor can electrically contact at least one of the shielding filmssuch that grounding the given ground conductor also grounds theshielding film or films. Such a ground conductor may also be referred toas a “drain wire”. Electrical contact between the shielding film and theground conductor may be characterized by a relatively low DC resistance,e.g., a DC resistance of less than 10 ohms, or less than 2 ohms, or ofsubstantially 0 ohms. In some cases, a given ground conductors may notelectrically contact the shielding films, but may be an individualelement in the cable construction that is independently terminated toany suitable individual contact element of any suitable terminationcomponent, such as, e.g., a conductive path or other contact element ona printed circuit board, paddle board, or other device. Such a groundconductor may also be referred to as a “ground wire”. FIG. 39 aillustrates an exemplary shielded electrical cable in which groundconductors are positioned external to the shielding films. FIGS. 39 band 39 c illustrate embodiments in which the ground conductors arepositioned between the shielding films, and may be included in theconductor set. One or more ground conductors may be placed in anysuitable position external to the shielding films, between the shieldingfilms, or a combination of both.

Referring to FIG. 39 a, a shielded electrical cable 21602 a includes asingle conductor set 21604 a that extends along a length of the cable21602 a. Conductor set 21604 a has two insulated conductors 21606, i.e.,one pair of insulated conductors, separated by dielectric gap 21630.Cable 21602 a may be made to have multiple conductor sets 21604 a spacedapart from each other across a width of the cable and extending along alength of the cable. Two shielding films 21608 a disposed on oppositesides of the cable include cover portions 21607 a. In transverse crosssection, the cover portions 21607 a, in combination, substantiallysurround conductor set 21604 a. An optional adhesive layer 21610 a isdisposed between pinched portions 21609 a of the shielding films 21608a, and bonds shielding films 21608 a to each other on both sides ofconductor set 21604 a. Insulated conductors 21606 are arranged generallyin a single plane and effectively in a twinaxial cable configurationthat can be used in a single ended circuit arrangement or a differentialpair circuit arrangement. The shielded electrical cable 21602 a furtherincludes a plurality of ground conductors 21612 positioned external toshielding films 21608 a. Ground conductors 21612 are placed over, under,and on both sides of conductor set 21604 a. Optionally, the cable 21602a includes protective films 21620 surrounding the shielding films 21608a and ground conductors 21612. Protective films 21620 include aprotective layer 21621 and an adhesive layer 21622 bonding protectivelayer 21621 to shielding films 21608 a and ground conductors 21612.Alternatively, shielding films 21608 a and ground conductors 21612 maybe surrounded by an outer conductive shield, such as, e.g., a conductivebraid, and an outer insulative jacket (not shown).

Referring to FIG. 39 b, a shielded electrical cable 21602 b includes asingle conductor set 21604 b that extends along a length of cable 21602b. Conductor set 21604 b has two insulated conductors 21606, i.e., onepair of insulated conductors, separated by dielectric gap 21630. Cable21602 b may be made to have multiple conductor sets 21604 b spaced apartfrom each other across a width of the cable and extending along thelength of the cable. Two shielding films 21608 b are disposed onopposite sides of the cable 21602 b and include cover portions 21607 b.In transverse cross section, the cover portions 21607 b, in combination,substantially surround conductor set 21604 b. An optional adhesive layer21610 b is disposed between pinched portions 21609 b of the shieldingfilms 21608 b and bonds the shielding films to each other on both sidesof the conductor set. Insulated conductors 21606 are arranged generallyin a single plane and effectively in a twinaxial or differential paircable arrangement. Shielded electrical cable 21602 b further includes aplurality of ground conductors 21612 positioned between shielding filmsv1608 b. Two of the ground conductors 21612 are included in conductorset 21604 b, and two of the ground conductors 21612 are spaced apartfrom conductor set 21604 b.

Referring to FIG. 39 c, a shielded electrical cable 21602 c includes asingle conductor set 21604 c that extends along a length of cable 21602c. Conductor set 21604 c has two insulated conductors 21606, i.e., onepair of insulated conductors, separated by dielectric gap 21630. Cable21602 c may be made to have multiple conductor sets 21604 c spaced apartfrom each other across a width of the cable and extending along thelength of the cable. Two shielding films 21608 c are disposed onopposite sides of the cable 21602 c and include cover portions 21607 c.In transverse cross section, the cover portions 21607 c, in combination,substantially surround the conductor set 21604 c. An optional adhesivelayer 21610 c is disposed between pinched portions 21609 c of theshielding films 21608 c and bonds shielding films 21608 c to each otheron both sides of conductor set 21604 c. Insulated conductors 21606 arearranged generally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement. Shielded electrical cable 21602 cfurther includes a plurality of ground conductors 21612 positionedbetween shielding films 21608 c. All of the ground conductors 21612 areincluded in the conductor set 21604 c. Two of the ground conductors21612 and insulated conductors 21606 are arranged generally in a singleplane.

In FIG. 36 c, an exemplary shielded electrical cable 20902 is shown intransverse cross section that includes two insulated conductors in aconnector set 20904, the individually insulated conductors 20906 eachextending along a length of the cable 20902 and separated bydielectric/air gap 20944. Two shielding films 20908 are disposed onopposite sides of the cable 20902 and in combination substantiallysurround conductor set 20904. An optional adhesive layer 20910 isdisposed between pinched portions 20909 of the shielding films 20908 andbonds shielding films 20908 to each other on both sides of conductor set20904 in the pinched regions 918 of the cable. Insulated conductors 906can be arranged generally in a single plane and effectively in atwinaxial cable configuration. The twinaxial cable configuration can beused in a differential pair circuit arrangement or in a single endedcircuit arrangement. Shielding films 20908 may include a conductivelayer 908 a and a non-conductive polymeric layer 20908 b, or may includethe conductive layer 908 a without the non-conductive polymeric layer20908 b. In the figure, the conductive layer 20908 a of each shieldingfilm is shown facing insulated conductors 20906, but in alternativeembodiments, one or both of the shielding films may have a reversedorientation.

The cover portion 20907 of at least one of the shielding films 20908includes concentric portions 20911 that are substantially concentricwith corresponding end conductors 20906 of the conductor set 20904. Inthe transition regions of the cable 20902, transition portion 20934 ofthe shielding films 20908 are between the concentric portions 20911 andthe pinched portions 20909 of the shielding films 20908. Transitionportions 20934 are positioned on both sides of conductor set 20904, andeach such portion includes a cross-sectional transition area 20934 a.The sum of cross-sectional transition areas 934 a is preferablysubstantially the same along the length of conductors 20906. Forexample, the sum of cross-sectional areas 20934 a may vary less than 50%over a length of 1 m.

In addition, the two cross-sectional transition areas 20934 a may besubstantially the same and/or substantially identical. Thisconfiguration of transition regions contributes to a characteristicimpedance for each conductor 20906 (single-ended) and a differentialimpedance that both remain within a desired range, such as, e.g., within5-10% of a target impedance value over a given length, such as, e.g., 1m. In addition, this configuration of the transition regions mayminimize skew of the two conductors 20906 along at least a portion oftheir length.

When the cable is in an unfolded, planar configuration, each of theshielding films may be characterizable in transverse cross section by aradius of curvature that changes across a width of the cable 20902. Themaximum radius of curvature of the shielding film 20908 may occur, forexample, at the pinched portion 20909 of the cable 20902, or near thecenter point of the cover portion 20907 of the multi-conductor cable set20904 illustrated in FIG. 36 c. At these positions, the film may besubstantially flat and the radius of curvature may be substantiallyinfinite. The minimum radius of curvature of the shielding film 20908may occur, for example, at the transition portion 20934 of the shieldingfilm 20908. In some embodiments, the radius of curvature of theshielding film across the width of the cable is at least about 50micrometers, i.e., the radius of curvature does not have a magnitudesmaller than 50 micrometers at any point along the width of the cable,between the edges of the cable. In some embodiments, for shielding filmsthat include a transition portion, the radius of curvature of thetransition portion of the shielding film is similarly at least about 50micrometers.

In an unfolded, planar configuration, shielding films that include aconcentric portion and a transition portion are characterizable by aradius of curvature of the concentric portion, R1, and/or a radius ofcurvature of the transition portion r1. These parameters are illustratedin FIG. 36 c for the cable 20902. In exemplary embodiments, R1/r1 is ina range of 2 to 15.

In FIG. 36 d another exemplary shielded electrical cable 21002 is shownwhich includes a conductor set having two insulated conductors 21006separated by dielectric/air gap 1014. In this embodiment, the shieldingfilms 21008 have an asymmetric configuration, which changes the positionof the transition portions relative to a more symmetric embodiment. InFIG. 36 d, shielded electrical cable 21002 has pinched portions 21009 ofshielding films 21008 that lie in a plane that is slightly offset fromthe plane of symmetry of the insulated conductors. 21006. As a result,the transition regions 21036 have a somewhat offset position andconfiguration relative to other depicted embodiments. However, byensuring that the two transition regions 21036 are positionedsubstantially symmetrically with respect to corresponding insulatedconductors 21006 (e.g. with respect to a vertical plane between theconductors 21006), and that the configuration of transition regions 1036is carefully controlled along the length of shielded electrical cable21002, the shielded electrical cable 21002 can be configured to stillprovide acceptable electrical properties.

In FIG. 36 e, additional exemplary shielded electrical cables areillustrated. These figures are used to further explain how a pinchedportion of the cable is configured to electrically isolate a conductorset of the shielded electrical cable. The conductor set may beelectrically isolated from an adjacent conductor set (e.g., to minimizecrosstalk between adjacent conductor sets) or from the externalenvironment of the shielded electrical cable (e.g., to minimizeelectromagnetic radiation escape from the shielded electrical cable andminimize electromagnetic interference from external sources). In bothcases, the pinched portion may include various mechanical structures torealize the electrical isolation. Examples include close proximity ofthe shielding films, high dielectric constant material between theshielding films, ground conductors that make direct or indirectelectrical contact with at least one of the shielding films, extendeddistance between adjacent conductor sets, physical breaks betweenadjacent conductor sets, intermittent contact of the shielding films toeach other directly either longitudinally, transversely, or both, andconductive adhesive, to name a few.

FIG. 36 e shows, in cross section, a shielded electrical cable 21102that includes two conductor sets 21104 a, 2104 b spaced apart across awidth of the cable 20102 and extending longitudinally along a length ofthe cable. Each conductor set 21104 a, 21104 b has two insulatedconductors 21106 a, 21106 b separated by gaps 21144. Two shielding films21108 are disposed on opposite sides of the cable 21102. In transversecross section, cover portions 21107 of the shielding films 21108substantially surround conductor sets 21104 a, 21104 b in cover regions21114 of the cable 21102. In pinched regions 21118 of the cable, on bothsides of the conductor sets 21104 a, 21104 b, the shielding films 21108include pinched portions 21109. In shielded electrical cable 21102, thepinched portions 21109 of shielding films 21108 and insulated conductors21106 are arranged generally in a single plane when the cable 21102 isin a planar and/or unfolded arrangement. Pinched portions 21109positioned in between conductor sets 21104 a, 21104 b are configured toelectrically isolate conductor sets 21104 a, 21104 b from each other.When arranged in a generally planar, unfolded arrangement, asillustrated in FIG. 36 e, the high frequency electrical isolation of thefirst insulated conductor 21106 a in the conductor set 21104 a relativeto the second insulated conductor 21106 b in the conductor set 21104 ais substantially less than the high frequency electrical isolation ofthe first conductor set 21104 a relative to the second conductor set21104 b.

As illustrated in the cross section of FIG. 36 e, the cable 21102 can becharacterized by a maximum separation, D, between the cover portions21107 of the shielding films 21108, a minimum separation, d2, betweenthe cover portions 21107 of the shielding films 21108, and a minimumseparation, d1, between the pinched portions 21109 of the shieldingfilms 21108. In some embodiments, d1/D is less than 0.25, or less than0.1. In some embodiments, d2/D is greater than 0.33.

An optional adhesive layer may be included as shown between the pinchedportions 21109 of the shielding films 21108. The adhesive layer may becontinuous or discontinuous. In some embodiments, the adhesive layer mayextend fully or partially in the cover region 21114 of the cable v1102,e.g., between the cover portion 21107 of the shielding films 21108 andthe insulated conductors 21106 a, 21106 b. The adhesive layer may bedisposed on the cover portion 21107 of the shielding film 21108 and mayextend fully or partially from the pinched portion 21109 of theshielding film 21108 on one side of a conductor set 21104 a, 21104 b tothe pinched portion 21109 of the shielding film 21108 on the other sideof the conductor set 21104 a, 21104 b.

The shielding films 21108 can be characterized by a radius of curvature,R, across a width of the cable 21102 and/or by a radius of curvature,r1, of the transition portion 21112 of the shielding film and/or by aradius of curvature, r2, of the concentric portion 21111 of theshielding film.

In the transition region 21136, the transition portion 21112 of theshielding film 21108 can be arranged to provide a gradual transitionbetween the concentric portion 21111 of the shielding film 21108 and thepinched portion 1109 of the shielding film 21108. The transition portion21112 of the shielding film 1108 extends from a first transition point21121, which is the inflection point of the shielding film 1108 andmarks the end of the concentric portion 21111, to a second transitionpoint 21122 where the separation between the shielding films exceeds theminimum separation, d1, of the pinched portions 21109 by a predeterminedfactor.

In some embodiments, the cable 21102 includes at least one shieldingfilm that has a radius of curvature, R, across the width of the cablethat is at least about 50 micrometers and/or the minimum radius ofcurvature, r1, of the transition portion 21112 of the shielding film21102 is at least about 50 micrometers. In some embodiments, the ratioof the minimum radius of curvature of the concentric portion to theminimum radius of curvature of the transition portion, r2/r1, is in arange of 2 to 15.

In some embodiments, the radius of curvature, R, of the shielding filmacross the width of the cable is at least about 50 micrometers and/orthe minimum radius of curvature in the transition portion of theshielding film is at least 50 micrometers.

In some cases, the pinched regions of any of the described shieldedcables can be configured to be laterally bent at an angle α of at least30°, for example. This lateral flexibility of the pinched regions canenable the shielded cable to be folded in any suitable configuration,such as, e.g., a configuration that can be used in a round cable. Insome cases, the lateral flexibility of the pinched regions is enabled byshielding films that include two or more relatively thin individuallayers. To warrant the integrity of these individual layers inparticular under bending conditions, it is preferred that the bondsbetween them remain intact. The pinched regions may for example have aminimum thickness of less than about 0.13 mm, and the bond strengthbetween individual layers may be at least 17.86 g/mm (1 lbs/inch) afterthermal exposures during processing or use.

In FIG. 36 f a shielded electrical cable 21302 is shown having only oneshielding film 21308. Insulated conductors 21306 are arranged into twoconductor sets 21304, each having only one pair of insulated conductorsseparated by dielectric/gaps 21314, although conductor sets having othernumbers of insulated conductors as discussed herein are alsocontemplated. Shielded electrical cable 21302 is shown to include groundconductors 21312 in various exemplary locations, but any or all of themmay be omitted if desired, or additional ground conductors can beincluded. The ground conductors 21312 extend in substantially the samedirection as insulated conductors 21306 of conductor sets 1304 and arepositioned between shielding film 21308 and a carrier film 21346 whichdoes not function as a shielding film. One ground conductor 21312 isincluded in a pinched portion 21309 of shielding film 21308, and threeground conductors 21312 are included in one of the conductor sets 21304.One of these three ground conductors 21312 is positioned betweeninsulated conductors v1306 and shielding film 21308, and two of thethree ground conductors 21312 are arranged to be generally co-planarwith the insulated conductors 21306 of the conductor set.

In addition to signal wires, drain wires, and ground wires, any of thedisclosed cables can also include one or more individual wires, whichare typically insulated, for any purpose defined by a user. Theseadditional wires, which may for example be adequate for powertransmission or low speed communications (e.g. less than 1 MHz) but notfor high speed communications (e.g. greater than 1 GHz), can be referredto collectively as a sideband. Sideband wires may be used to transmitpower signals, reference signals or any other signal of interest. Thewires in a sideband are typically not in direct or indirect electricalcontact with each other, but in at least some cases they may not beshielded from each other. A sideband can include any number of wiressuch as 2 or more, or 3 or more, or 5 or more.

The shielded cable configurations described herein provide opportunitiesfor simplified connections to the conductor sets and/or drain/groundwires that promote signal integrity, support industry standardprotocols, and/or allow mass termination of the conductor sets and drainwires. In the cover regions, the conductor sets are substantiallysurrounded by shielding films and the conductor sets are separated fromone another by the pinched regions. These circuit configurations mayprovide intra-cable electrical isolation between the conductor setswithin the cable, provide extra-cable isolation between the conductorsets of the cable and the external environment, require fewer drainwires, and/or allow drain wires to be spaced apart from the conductorsets, for example.

As previously illustrated and/or described, the shielding films mayinclude concentric regions, pinched regions and transition regions thata gradual transition between the concentric regions and the pinchedregions. The geometry and uniformity of the concentric regions, pinchedregions, and/or transition regions impact the electrical characteristicsof the cable. It is desirable to reduce and/or control, the impactcaused by non-uniformities in the geometry of these regions. Maintaininga substantially uniform geometry (e.g., size, shape, content, and radiusof curvature) along the length of a cable can favorably influence theelectrical characteristics of the cable. With regard to the transitionregions, it may be desirable to reduce the size and/or to control thegeometric uniformity of these regions. For example, a reduction in theinfluence of the transition regions can be achieved by reducing the sizeof the transition region and/or carefully controlling the configurationof the transition region along the length of the shielded electricalcable. Reducing the size of the transition region reduces thecapacitance deviation and reduces the required space between multipleconductor sets, thereby reducing the conductor set pitch and/orincreasing the electrical isolation between conductor sets. Carefulcontrol of the configuration of the transition region along the lengthof the shielded electrical cable contributes to obtaining predictableelectrical behavior and consistency, which provides for high speedtransmission lines so that electrical data can be more reliablytransmitted. Careful control of the configuration of the transitionregion along the length of the shielded electrical cable is a factor asthe size of the transition portion approaches a lower size limit.

Electrical characteristics of a cable determine the cable's suitabilityfor high speed signal transmission. Electrical characteristics of acable include characteristic impedance, insertion loss, crosstalk, skew,eye opening, and jitter, among other characteristics. The electricalcharacteristics can depend on the physical geometry of the cable, aspreviously discussed, and can also depend on the material properties ofthe cable components. Thus is it generally desirable to maintainsubstantially uniform physical geometry and/or material properties alongthe cable length. For example, the characteristic impedance of anelectrical cable depends on the physical geometry and materialproperties of the cable. If a cable is physically and materially uniformalong its length, then the characteristic impedance of the cable willalso be uniform. However, non-uniformities in the geometry and/ormaterial properties of the cable cause a mismatches in the impedance atthe points of non-uniformity. The impedance mismatches can causereflections that attenuate the signal and increase the insertion loss ofthe cable. Thus, maintaining some uniformity in the physical geometryand material properties along the cable length can improve theattenuation characteristics of the cable. Some typical characteristicimpedances for exemplary electrical cables described herein are 50 ohms,75 ohms, and 100 ohms, for example. In some cases, the physical geometryand material properties of the cables described herein may be controlledto produce variations in the characteristic impedance of the cable ofless than 5% or less than 10%.

Insertion loss of a cable (or other component) characterizes the totalloss of signal power attributable to that component. The term insertionloss is often used interchangeably with the term attenuation.Attenuation is sometimes defined as all losses caused by a componentexcluding the impedance mismatch losses. Thus, for a perfectly matchedcircuit, insertion loss is equal to attenuation. Insertion loss of acable includes reflection loss (loss due to mismatches in characteristicimpedance), coupling loss (loss due to crosstalk), conductor loss(resistive loss in the signal conductors), dielectric loss (loss in thedielectric material), radiation loss (loss due to radiated energy), andresonance loss (loss due to resonance in the cable). Insertion loss maybe expressed in dB as:

${{{Insertionloss}({dB})} = {10\;\log_{10}\frac{P_{T}}{P_{R}}}},$where P_(T) is the signal power transmitted and P_(R) is the signalpower received. Insertion loss is dependent on the signal frequency.

For cables, or other components of variable length, insertion loss maybe expressed per unit length, e.g., as dB/meter. FIGS. 40 a and 40 b aregraphs of insertion loss vs. frequency for shielded cables describedherein over a frequency range of 0 to 20 GHz. The cables tested were 1meter in length, with twinaxial sets of 30 AWG conductors, and 100 ohmcharacteristic impedance.

FIG. 40 is a graph of the insertion loss (SDD12) of Cable 1 which hassilver plated 30 AWG conductors. FIG. 41 is a graph of the insertionloss (SDD12) of Cable 2 which has tin plated 30 AWG conductors. As shownin FIGS. 40 and 41, at a frequency of 5 GHz, Cable 2 (30 AWG tin platedconductors) has an insertion loss of less than about −5 dB/m or evenless than about −4 dB/m. At a frequency of 5 GHz, Cable 1 (30 AWG silverplated conductors) has an insertion loss of less than about −5 dB/m, orless than about −4 dB, or even less than about −3 dB/m. Over the entirefrequency range of 0 to 20 GHz, Cable 2 (30 AWG tin plated conductors)has an insertion loss less than about −30 dB/m, or less than about −20dB/m, or even less than about −15 dB/m. Over the entire frequency rangeof 0 to 20 GHz, Cable 1 (30 AWG silver plated conductors) has aninsertion loss of less than about −20 dB/m, or even less than about −15dB/m, or even less than about −10 dB/m.

All other factors being constant, attenuation is inversely proportionalto conductor size. For the shielded cables described in the disclosure,at a frequency of 5 GHz a cable with tin plated signal conductors of asize no smaller than 24 AWG has an insertion loss of less than about −5dB/m or even less than about −4 dB/m. At a frequency of 5 GHz cable withsilver plated signal conductors of a size no smaller than 24 AWG has aninsertion loss of less than about −5 dB/m, or less than about −4 dB, oreven less than about −3 dB/m. Over the entire frequency range of 0 to 20GHz, a cable with tin plated signal conductors of a size no smaller than24 AWG has an insertion loss less than about −25 dB/m, or less thanabout −20 dB/m, or even less than about −15 dB/m. Over the entirefrequency range of 0 to 20 GHz, a cable with silver plated signalconductors of a size no smaller than 24 AWG has an insertion loss ofless than about −20 dB/m, or even less than about −15 dB/m, or even lessthan about −10 dB/m.

The cover portions and pinched portions help to electrically isolate theconductor sets in the cable from each other and/or to electricallyisolate the conductor sets from the external environment. The shieldingfilms discussed herein can provide the closest shield for the conductorsets, however additional, auxiliary shielding disposed over theseclosest shielding films may additionally be used to increase intra-cableand/or extra-cable isolation.

In contrast to using one or more shielding films disposed on one or moresides of the cable with cover portions and pinched portions as describedherein, some types of cables helically wrap a conductive film aroundindividual conductor sets as a closest shield or as an auxiliary shield.In the case of twinaxial cables used to carry differential signals, thepath of the return current is along opposite sides of the shield. Thehelical wrap creates gaps in the shield resulting in discontinuities inthe current return path. The periodic discontinuities produce signalattenuation due to resonance of the conductor set. This phenomenon isknown as “signal suck-out” and can produce significant signalattenuation that occurs at a particular frequency range corresponding tothe resonance frequency.

FIG. 42 illustrates a twinaxial cable 7200, (referred to herein as Cable3) that has a helically wrapped film 7208 around the conductor set 7205as a closest shield. FIG. 43 shows a cross section of a cable 7300,(referred to herein as Cable 4) having a cable configuration previouslydescribed herein including a twinaxial conductor set 7305 having 30 AWGconductors 7304, two 32 AWG drain wires 7306 and two shielding films7308 on opposite sides of the cable 7300. The shielding films 7308include cover portions 7307 that substantially surround the conductorset 7305 and pinched portions 7309 on either side of the conductor set7305. Cable 4 has silver plated conductors and polyolefin insulation.

The graphs of FIG. 44 compare the insertion loss due to resonance ofCable 3 with that of Cable 4 The insertion loss due to resonance peaksin the insertion loss graph of Cable 3 at about 11 GHz. In contrast,there is no insertion loss due to resonance observable in the insertionloss graph of Cable 4. Note that in these graphs, attenuation due to theterminations of the cable are also present.

The attenuation due to resonance of Cable 3 can be characterizable by aratio between a nominal signal attenuation, N_(SA), and the signalattenuation due to resonance, R_(SA), wherein N_(SA) is a lineconnecting the peaks of the resonance dip and R_(SA) is the attenuationat the valley of the resonance dip. The ratio between N_(SA) and R_(SA)for Cable 3 at 11 GHz is about −11 dB/−35 dB or about 0.3. In contrast,Cable 4 has N_(SA)/R_(SA) values of about 1 (which corresponds to zeroattenuation due to resonance) or at least greater than about 0.5.

The insertion loss of cables having the cross sectional geometry ofCable 4 were tested at three different lengths, 1 meter (Cable 5), 1.5meters (Cable 6), and 2 meters (Cable 7) The insertion loss graphs forthese cables is shown in FIG. 45. No resonance is observed for thefrequency range of 0 to 20 GHz. (Note the slight dip near 20 GHz isassociated with the termination and is not a resonance loss.)

As illustrated in FIG. 46, instead of using a helically wrapped shield,some types of cables 7600 include a longitudinally folded a sheet orfilm of conductive material 7608 around the conductor sets 7605 to formthe closest shield. The ends 7602 of the longitudinally folded shieldfilm 7606 may be overlapped and/or the ends of the shield film may besealed with a seam. Cables having longitudinally folded closest shieldsmay be overwrapped with one or more auxiliary shields 7609 prevent theoverlapped edges and/or the seam from separating when the cable is bent.The longitudinal folding may mitigate the signal attenuation due toresonance by avoiding the periodicity of the shield gaps caused byhelically wrapping the shield, however the overwrapping to preventshield separation increases the shield stiffness.

Cables with cover portions that substantially surround the conductorsets and pinched portions located on each side of the conductor set asdescribed herein do not rely on a helically wrapped closest shield toelectrically isolate the conductor sets and do not rely on a closestshield that is longitudinally folded around the conductor sets toelectrically isolate the conductors sets. Helically wrapped and/orlongitudinally folded shields may or may not be employed as auxiliaryshields external to the cables described.

Cross talk is caused by the unwanted influence of magnetic fieldsgenerated by nearby electrical signals. Crosstalk (near and far-end) isa consideration for signal integrity in cable assemblies. Near end crosstalk is measured at the transmitting end of the cable. Far end crosstalk is measured at the receiving end of the cable. Crosstalk is noisethat arises in a victim signal from unwanted coupling from an aggressorsignal. Close spacing between the signal lines in the cable and/or inthe termination area can be susceptible to crosstalk. The cables andconnectors described herein approaches to reduce crosstalk. For example,crosstalk in the cable can be reduced if the concentric portions,transition portions, and/or pinched portions of the shielding films incombination form as complete a shield surrounding the conductor sets aspossible. In the cable, cross talk is reduced if there any gaps betweenthe shields, then making that gap have as high an aspect ratio aspossible and/or by using low impedance or direct electrical contactbetween the shields. For example, the shields may be in direct contact,in connected through drain wires, and/or connected through a conductiveadhesive, for example. At electrical contact sites between theconductors of the cable and the terminations of a connector, crosstalkcan be reduced by increasing the separation between the contact points,thus reducing the inductive and capacitive coupling.

FIG. 47 illustrates the far end crosstalk (FEXT) isolation between twoadjacent conductor sets of a conventional electrical cable wherein theconductor sets are completely isolated, i.e., have no common ground(Sample 1), and between two adjacent conductor sets of shieldedelectrical cable 2202 illustrated in FIG. 15 a wherein shielding films2208 are spaced apart by about 0.025 mm (Sample 2), both having a cablelength of about 3 m. The test method for creating this data is wellknown in the art. The data was generated using an Agilent 8720ES 50MHz-20 GHz S-Parameter Network Analyzer. It can be seen by comparing thefar end crosstalk plots that the conventional electrical cable andshielded electrical cable 2202 provide a similar far end crosstalkperformance. Specifically, it is generally accepted that a far endcrosstalk of less than about −35 dB is suitable for most applications.It can be easily seen from FIG. 47 that for the configuration tested,both the conventional electrical cable and shielded electrical cable2202 provide satisfactory electrical isolation performance. Thesatisfactory electrical isolation performance in combination with theincreased strength of the parallel portion due to the ability to spaceapart the shielding films is an advantage of a shielded electrical cableaccording to an aspect of the present invention over conventionalelectrical cables.

Propagation delay and skew are additional electrical characteristics ofelectrical cables. Propagation delay depends on the velocity factor ofthe cable and is the amount of time that it takes for a signal to travelfrom one end of the cable to the opposite end of the cable. Thepropagation delay of the cable may be an important consideration insystem timing analysis.

relative to an adjacent conductor set.

The high frequency isolation of the first insulated conductor relativeto the second conductor is a first far end crosstalk C1 at a specifiedfrequency range of about 5, to about 15 GHz and a length of 1 meter. Thehigh frequency isolation of the first conductor set relative to theadjacent conductor set is a second far end crosstalk C2 at the specifiedfrequency. C2 can be at least 10 dB lower than C1.

The difference in propagation delay between two or more conductors in acable is referred to as skew. Low skew is generally desirable betweenconductors of a cable used in single ended circuit arrangements andbetween conductors used as a differential pair. Skew between multipleconductors of a cable used in single ended circuit arrangements canaffect overall system timing. Skew between two conductors used in adifferential pair circuit arrangement is also a consideration. Forexample, conductors of a differential pair that have different lengths(or different velocity factors) can result in skew between the signalsof the differential pairs. Differential pair skew may increase insertionloss, impedance mismatch, and/or crosstalk, and/or can result in ahigher bit error rate and jitter. Skew produces conversion of thedifferential signal to a common mode signal that can be reflected backto the source, reduces the transmitted signal strength, createselectromagnetic radiation, and can dramatically increase the bit errorrate, in particular jitter. Ideally, a pair of transmission lines willhave no skew, but, depending on the intended application, a differentialS-parameter SCD21 or SCD12 value (representing the differential-tocommon mode conversion from one end of the transmission line to theother) of less than −25 to −30 dB up to a frequency of interest, suchas, e.g., 6 GHz, may be acceptable.

Skew of a cable can be expressed as a difference in propagation delayper meter for the conductors in a cable per unit length. Intrapair skewis the skew within a twinaxial pair and interpair skew is the skewbetween two pairs. There is also skew for two single coax or other evenunshielded wires. Shielded electrical cables described herein mayachieve skew values of less than about 20 picoseconds/meter (psec/m) orless than about 10 psec/m at data rates up to about 10 Gbps.

Jitter is a complex characteristic that involves skews, reflections,pattern dependent interference, propagation delays, and coupled noisethat reduce signal quality. Some standards have defined jitter as thetime deviation between a controlled signal edge from its nominal value.In digital signals, jitter may be considered as the portion of a signalwhen switching from one logic state to another logic state that thedigital state is indeterminate. The eye pattern is a useful tool formeasuring overall signal quality because it includes the effects ofsystemic and random distortions. The eye pattern can be used to measurejitter at the differential voltage zero crossing during the logic statetransition. Typically, jitter measurements are given in units of time oras a percentage of a unit interval. The “openness” of the eye reflectsthe level of attenuation, jitter, noise, and crosstalk present in thesignal.

Electrical specifications for 4 cable types tested are provided in Table1. Two of the tested cables, Sn1, Sn2, include sidebands, e.g., lowfrequency signal cables. Two of the cables tested, Sn2, Ag2 did notinclude sidebands.

TABLE 1 Insertion loss and skew for four types of shielded electricalcable Insertion loss Cable Configuration (@ 5 GHz) Skew Sn1 4 signalpairs, 2 outside grounds, −4 dB/m <10 ps/m 4 sidebands (picoseconds/ Snplated, 30 AWG, Polyolefin meter) dielectric Ag1 4 signal pairs, 2outside grounds −3 dB/m <10 ps/m 4 sidebands Ag plated, 30 AWG,Polyolefin dielectric Sn2 4 signal pairs, 2 outside grounds −4 dB/m <10ps/m No sideband Ag plated, 30 AWG, Polyolefin dielectric Ag1 4 signalpairs, 2 outside grounds −3 dB/m <10 ps/m 4 sidebands Ag plated, 30 AWG,Polyolefin dielectric

As previously discussed helically wrapped shields, longitudinally foldedshields, and/or overwrapped shields can undesirably increase cablestiffness. Some of the cable configurations described herein, such asthe cable configuration shown in FIG. 43 can provide similar or betterinsertion loss characteristics to cables having helically wrapped,longitudinally folded and/or overwrapped shields but also providereduced stiffness.

The stiffness of a cable is characterizable as an amount of force neededto deflect the cable by a distance. In reference now to FIG. 48, a blockdiagram illustrates a test setup 7800 for measuring deflection of acable 7801 according to an example embodiment of the invention. In thissetup, the cable 7801 is initially laid flat across roller-type supports7802 as indicated by dashed lines. The supports 7802 prevent downwardmotion, but otherwise allow free movement of the cable in a side-to-sidedirection. This may be analogous to the constraint of a simply supportedbeam, e.g., a beam that has hinged connection at one end and rollerconnection in other end.

The supports 7802 in this test setup were 2.0 inch diameter cylindersseparated by a constant distance 7804 of 5.0 inches between the topsides of the cylinders (e.g., 12 o'clock position when viewed from theperspective seen in FIG. 48). A force 7806 is applied to the cable 7801via a force actuator 7810 at a point equidistant between supports 7804,and deflection 7808 is measured. The force actuator 7810 is a 0.375 inchdiameter cylinder, driven at a 5.0 inches per minute crosshead speed.

Results of a first test using setup 7800 for cables disclosed herein areshown in graph 7900 of FIG. 49 Curve 7902 represents force-deflectionresults for a ribbon cable (e.g., similar to the configuration of FIG.43) with two solid 30 AWG conductors, solid polyolefin insulation, andtwo 32 AWG drain wires. The maximum force is approximately 0.025 lbs,and occurs at approximately 1.2 inches of deflection. By way of a roughcomparison, curve 7904 was measured for a wrapped twinax cable havingtwo 30 AWG wires, and two 30 AWG drain wires. This curve has maximumforce of around 0.048 lbs at a deflection of 1.2 inches. All thingsbeing equal, it would be expected that the twinax cable would beslightly stiffer due to the thicker (30 AWG vs. 32 AWG) drain wiresused, however this would not explain the significant difference betweencurves 7902 and 7904. Generally, it is expected that the application ofthe force of 0.03 lbf on the cable represented by curve 7902 midpointbetween the supporting points causes the deflection in the direction ofthe force of at least 1 inch. It should be apparent that the cablerepresented by curve 7904 would deflect about half that much.

In FIG. 50, a graph 8000 includes results of a subsequent test of cablesaccording to example embodiments of the invention using the forcedeflection setup of FIG. 48. For each of four wire gauges (24, 26, 30,and 32 AWG), four, cables were constructed, each having exactly twosolid wire conductors of the respective gauges. The cables hadpolypropylene insulation with shielding on both sides, and no drainwires. The force was measured for every 0.2 inches of deflection. Table2 below summarizes the results at the maximum force points 8002, 8004,8006, 8008, which respectively correspond to the results for the sets ofcables with respective conductor gauge sizes of 24, 26, 30, and 32 AWG.The fifth and sixth columns of Table 2 correspond to the respectivehighest and lowest maximum forces of the four cables tested within eachgauge group.

TABLE 2 Force-deflection results for shielded ribbon cables with oneconductor pair Conductor Deflection at Average Standard Max Min gaugemaximum maximum deviation force force (AWG) force (in.) force (lbf)(lbf) (lbf) (lbf) 24 1.2 0.207 0.005 0.214 0.202 26 1.2 0.111 0.0030.114 0.108 30 1.4 0.0261 0.002 0.0284 0.0241 32 1.4 0.0140 0.00060.0149 0.0137

For the data in Table 2, it is possible to perform a linear regressionof the form y=mx+b on the logarithms of conductor diameters versus thelogarithms of maximum deflection force. The natural logarithms (ln) ofthe forces in the third column of Table 2 are plotted versus naturallogarithms of the respective diameters in graph 8100 of FIG. 51. Thediameters of 24, 26, 30, and 32 AWG wires are 0.0201, 0.0159, 0.010, and0.008, respectively. A least squares linear regression of the curve ingraph 8100 results in the following fit: ln(F_(max))=2.96*ln(dia)+10.0.By solving for F_(max) and rounding to two significant figures, thefollowing empirical result is obtained:F _(max) =M*dia ³, where M=22,000 lbf/in³  [1]

Equation [1] predicts that a similar cable made using two 28 AWGconductors (diameter=0.0126) would bend at a maximum force of22,000*0.01263=0.044 lbf. Such a result is reasonable in view of theresults for other gauges shown in FIG. 49. Further, Equation [1] may bemodified to express the individual maximum force (F_(max-single)) foreach single insulated conductor as follows:F _(max-single) =M*dia ³, where M=11,000 lbf/in³  [2]

The individual forces calculated from [2] for each insulated conductor(and drain wires or other non-insulated conductors) may be combined toobtain a collective maximum bending force for a give cable. For example,a combination of two 30 AWG and two 32 AWG wires would be expected tohave a maximum bending resistance force of 0.0261+0.014=0.0301 lbf. Thisis higher than the 0.025 lbf value seen in curve 1802 of FIG. 18 for thetested cable that had a combination of 30 AWG insulated wires and 32 AWGdrain wires. However, such a difference may be expected. The drain wiresin the tested cable are not insulated, thereby making the tested cablemore flexible than the theoretical case. Generally, the results ofEquations [1] and [2] are expected to return a high-end limit of bendingforces, which would still be more flexible than a conventional wrappedcable. By way of comparison, using Equation [2] for four 30 AWG wires,the maximum force would be 4*11,000*0.01=0.044 lbf, which is below whatis seen with the conventional wrapped cable test curve 7804 in FIG. 48.If the drain wires in the wrapped cable were insulated (which was notthe case) the curve 7804 would be expected exhibit an even highermaximum force.

A number of other factors could alter the results predicted by Equations[1] and [2], including the type of wire insulation (polyethylene andfoamed insulation would likely be less stiff, and fluoropolymerinsulation more stiff), the type of wire (stranded wires would be lessstiff), etc. Nonetheless, Equations [1] and [2] may provide a reasonableestimate of maximum bending forces for a given cable assembly, andpresent ribbon cable constructions exhibiting such properties should bemeasurably more flexible than equivalent wrapped constructions.

Item 1 is a shielded electrical cable, comprising:

one or more conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set having one or more conductors having a size no greaterthan 24 AWG and each conductor set having an insertion loss of less than−20 dB/meter over a frequency range of 0 to 20 GHz; and

first and second shielding films disposed on opposite sides of thecable, the first and second films including cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films in combination substantiallysurround each conductor set, and the pinched portions of the first andsecond films in combination form pinched portions of the cable on eachside of each conductor, wherein a maximum separation between the firstcover portions of the first and second shielding films is D, a minimumseparation between the first pinched portions of the first and secondshielding films is d₁, and d₁/D is less than about 0.25.

Item 2 is the cable of item 1 , wherein the conductor set comprises twoconductors in a twinaxial arrangement and the insertion loss due toresonance of the conductor set is about zero.

Item 3 is the cable of item 1 , wherein the conductor set comprises twoconductors in a twinaxial arrangement, and a nominal insertion losswithout insertion loss due to resonance is about 0.5 times the insertionloss due to resonance of the conductor set.

Item 4 is the cable of item 1, further comprising an adhesive layerdisposed between the pinched portions of the shielding films.

Item 5 is the cable of item 1, wherein the insertion loss of eachconductor set is less than about −5 dB per meter.

Item 6 is the cable of item 1, wherein the insertion loss of eachconductor set is less than about −4 dB per meter.

Item 7 is the cable of item 1, wherein the insertion loss of eachconductor set is less than about −3 dB/meter.

Item 8 is the cable of item 1, wherein the cable has a skew of less thanabout 20 psec/meter at data transfer speeds of up to about 10 Gbps.

Item 9 is the cable of item 1, wherein the cable has a skew of less thanabout 10 psec/meter at data transfer speeds of up to about 10 Gbps.

Item 10 is the cable of item 1, wherein a characteristic impedance ofthe cable remains within 5-10% of a target characteristic impedance overa cable length of about 1 meter.

Item 11 is the cable of item 1, wherein the one or more conductor setscomprise a first conductor set and a second conductor set, eachconductor set having a first insulated conductor and a second insulatedconductor and a high frequency electrical isolation of the firstinsulated conductor relative to the second insulated conductor in eachconductor set is substantially less than a high frequency electricalisolation of the first conductor set relative to an adjacent conductorset.

Item 1 is the cable of item 1, wherein the high frequency isolation ofthe first insulated conductor relative to the second conductor is afirst far end crosstalk C1 at a specified frequency range of 3-15 GHzand a length of 1 meter, and the high frequency isolation of the firstconductor set relative to the adjacent conductor set is a second far endcrosstalk C2 at the specified frequency, and wherein C2 is at least 10dB lower than C1.

Item 13 is the cable of item 1, wherein d₁/D is less than 0.1.

Item 14 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set having two conductors having a size no greater than 24 AWGand each conductor set having a signal attenuation of less than −20dB/meter over a frequency range of 0 to 20 GHz; at least one drain wire;and

first and second shielding films disposed on opposite sides of thecable, the first and second shielding films including cover portions andpinched portions arranged such that, in transverse cross section, thecover portions of the first and second films, in combination,substantially surround each conductor set, and the pinched portions ofthe first and second films, in combination, form pinched portions of thecable on each side of each conductor set, wherein, for at least oneconductor set, a separation between the drain wire and a closestconductor of the conductor set is greater than 0.5 times a center tocenter spacing between the two conductors of the conductor set.

Item 15 is the cable of item 14, wherein the insertion loss of eachconductor set is less than about −5 dB per meter or less than about −4dB per meter, or less than about −3 dB per meter.

Item 16 is the cable of item 14, wherein the cable has a skew of lessthan about 20 psec/meter or less than about 10 psec/meter at datatransfer speeds up to about 10 Gbps.

Item 17 is the cable of item 14, wherein a characteristic impedance ofthe cable remains within 5-10% of a target characteristic impedance overa cable length of 1 meter.

Item 18 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor sets having two conductors arranged in a twinaxialconfiguration, each of the conductors having a size no greater than 24AWG; and

first and second shielding films disposed on opposite sides of thecable, neither shielding film comprising a longitudinal fold thatorients the shielding film to cover the conductor sets on both sides ofthe cable, wherein each conductor set has an insertion loss of less than−20 dB/meter over a frequency range of 0 to 20 GHz and an insertion lossdue to resonance of the conductor set is about zero.

Item 19 is the cable of item 18, further comprising at least one drainwire, wherein the first and second shielding films include coverportions and pinched portions arranged such that, in transverse crosssection, the cover portions of the first and second films, incombination, substantially surround each conductor set, and the pinchedportions of the first and second films, in combination, form pinchedportions of the cable on each side of each conductor set, wherein, forat least one conductor set, a separation between the drain wire and aclosest conductor of the conductor set is greater than 0.5 times acenter to center spacing between the two conductors of the conductorset.

Item 20 is the cable of item 18, wherein the insertion loss of eachconductor set is less than about −5 dB per meter or less than about −4dB per meter, or less than about −3 dB per meter.

Item 21 is the cable of item 18, wherein the cable has a skew of lessthan about 20 psec/meter or less than about 10 psec/meter.

Item 22 is the cable of item 18, wherein a characteristic impedance ofthe cable remains within 5-10% of a target characteristic impedance overa cable length of about 1 meter.

Item 23 is a shielded electrical cable, comprising:

a plurality of conductor extending along a length of the cable and beingspaced apart from each other along a width of the cable, each of theconductors sets comprising two conductors arranged in a twinaxialconfiguration, each conductor having a size no greater than 24 AWG; and

first and second shielding films disposed on opposite sides of thecable, neither shielding film comprising a seam that bonds the shieldingfilm to itself, wherein each conductor set has an insertion loss of lessthan −20 dB/meter over a frequency range of 0 to 20 GHz and an insertionloss due to resonance loss of the conductor set is about zero.

Item 24 is the cable of item 23, further comprising at least one drainwire, wherein the first and second shielding films include coverportions and pinched portions arranged such that, in transverse crosssection, the cover portions of the first and second films, incombination, substantially surround each conductor set, and the pinchedportions of the first and second films, in combination, form pinchedportions of the cable on each side of each conductor set, wherein, forat least one conductor set, a separation between the drain wire and aclosest conductor of the conductor set is greater than 0.5 times acenter to center spacing between the two conductors of the conductorset.

Item 25 is the cable of item 24, wherein a maximum separation betweenthe first cover portions of the first and second shielding films is D, aminimum separation between the first pinched portions of the first andsecond shielding films is d₁, and d₁/D is less than about 0.25.

Item 26 is the cable of item 24, wherein each shielding film,individually, surrounds less than all of a periphery of each conductorset.

The embodiments discussed in this disclosure have been illustrated anddescribed herein for purposes of description of the preferredembodiment, it will be appreciated by those of ordinary skill in the artthat a wide variety of alternate and/or equivalent implementationscalculated to achieve the same purposes may be substituted for thespecific embodiments shown and described without departing from thescope of the present invention. Those with skill in the mechanical,electro-mechanical, and electrical arts will readily appreciate that thepresent invention may be implemented in a very wide variety ofembodiments. This application is intended to cover any adaptations orvariations of the preferred embodiments discussed herein. Therefore, itis manifestly intended that this invention be limited only by the claimsand the equivalents thereof.

What is claimed is:
 1. A shielded electrical cable, comprising: aplurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set having two conductors arranged in a twinaxialconfiguration, each of the conductors having a size no greater than 24AWG; first and second shielding films disposed on opposite sides of thecable, neither shielding film comprising a longitudinal fold thatorients the shielding film to cover the conductor sets on both sides ofthe cable, wherein the first and second shielding films include coverportions and pinched portions arranged such that, in transverse crosssection, the cover portions of the first and second films, incombination, substantially surround each conductor set, and the pinchedportions of the first and second films, in combination, form pinchedportions of the cable on each side of each conductor set; and a drainwire, wherein, for at least one conductor set, a separation between thedrain wire and a closest conductor of the conductor set is greater than0.5 times a center to center spacing between the two conductors of theconductor set.
 2. The cable of claim 1, wherein each conductor set hasan insertion loss of less than −20 dB/meter over a frequency range of 0to 20 GHz and an insertion loss due to resonance of the conductor set isabout zero.
 3. A shielded electrical cable, comprising: a plurality ofconductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable, each of the conductorssets comprising two conductors arranged in a twinaxial configuration,each conductor having a size no greater than 24 AWG; first and secondshielding films disposed on opposite sides of the cable, neithershielding film comprising a seam that bonds the shielding film toitself, wherein the first and second shielding films include coverportions and pinched portions arranged such that, in transverse crosssection, the cover portions of the first and second films, incombination, substantially surround each conductor set, and the pinchedportions of the first and second films, in combination, form pinchedportions of the cable on each side of each conductor set and a drainwire, wherein, for at least one conductor set, a separation between thedrain wire and a closest conductor of the conductor set is greater than0.5 times a center to center spacing between the two conductors of theconductor set.
 4. The cable of claim 3, wherein each conductor set hasan insertion loss of less than −20 dB/meter over a frequency range of 0to 20 GHz and an insertion loss due to resonance loss of the conductorset is about zero.